diff --git a/collects/mred/private/mrtop.rkt b/collects/mred/private/mrtop.rkt
index 662e53194c..4fb5a7f78b 100644
--- a/collects/mred/private/mrtop.rkt
+++ b/collects/mred/private/mrtop.rkt
@@ -162,14 +162,8 @@
 	  (check-init-pos-integer cwho x)
 	  (check-init-pos-integer cwho y)
 	  (check-style cwho #f '(no-resize-border no-caption no-system-menu 
-						  mdi-parent mdi-child 
 						  toolbar-button hide-menu-bar float metal) 
-		       style)
-	  (when (memq 'mdi-child style)
-	    (when (memq 'mdi-parent style)
-	      (raise-type-error (who->name cwho) 
-				"style list, 'mdi-child and 'mdi-parent are mutually exclusive" 
-				style)))))
+		       style)))
       (rename [super-on-subwindow-char on-subwindow-char])
       (private-field
        [wx #f]
@@ -186,7 +180,6 @@
 		       (lambda (e)
 			 (check-instance '(method frame% on-menu-char) wx:key-event% 'key-event% #f e)
 			 (send wx handle-menu-key e)))]
-	[on-mdi-activate (lambda (on?) (void))]
 	[on-toolbar-button-click (lambda () (void))]
 	[create-status-line (entry-point (lambda () (unless status-line? (do-create-status-line) (set! status-line? #t))))]
 	[set-status-text (lambda (s) (do-set-status-text s))]
@@ -217,16 +210,12 @@
 					    (or x -11111) (or y -11111)
 					    (or width -1) (or height -1)
 					    style)
-			       (memq 'mdi-parent style)))
-	      (send wx set-mdi-parent (memq 'mdi-parent style))
+			       #f))
+	      (send wx set-mdi-parent #f)
 	      wx)
 	    (lambda ()
 	      (let ([cwho '(constructor frame)])
-		(check-container-ready cwho parent)
-		(when (memq 'mdi-child style)
-		  (let ([pwx (and parent (mred->wx parent))])
-		    (unless (and pwx (send pwx get-mdi-parent))
-		      (raise-mismatch-error (who->name cwho) "parent for 'mdi-child frame is not an 'mdi-parent frame: " parent))))))
+		(check-container-ready cwho parent)))
 	    label parent))))))
 
   (define dialog%
diff --git a/collects/scribblings/gui/frame-class.scrbl b/collects/scribblings/gui/frame-class.scrbl
index b7f14107f7..ce2eaec33d 100644
--- a/collects/scribblings/gui/frame-class.scrbl
+++ b/collects/scribblings/gui/frame-class.scrbl
@@ -7,9 +7,6 @@ A frame is a top-level container window. It has a title bar (which
  displays the frame's label), an optional menu bar, and an optional
  status line.
 
-On Windows, both Multiple Document Interface (MDI) and Single
- Document Interface (SDI) frames are supported.
-
 @defconstructor[([label label-string?]
                  [parent (or/c (is-a?/c frame%) false/c) #f]
                  [width (or/c (integer-in 0 10000) false/c) #f]
@@ -18,7 +15,6 @@ On Windows, both Multiple Document Interface (MDI) and Single
                  [y (or/c (integer-in -10000 10000) false/c) #f]
                  [style (listof (one-of/c 'no-resize-border 'no-caption 
                                           'no-system-menu 'hide-menu-bar 
-                                          'mdi-parent 'mdi-child
                                           'toolbar-button 'float 'metal)) null]
                  [enabled any/c #t]
                  [border (integer-in 0 1000) 0]
@@ -37,9 +33,8 @@ set-label]), the title bar is updated.
 
 The @racket[parent] argument can be @racket[#f] or an existing
 frame. On Windows, if @racket[parent] is an existing frame,
-the new frame is always on top of its parent. Also, the
-@racket[parent] frame may be an MDI parent frame from a new MDI
-child frame. On Windows and Unix (for many window managers), a
+the new frame is always on top of its parent.
+On Windows and Unix (for many window managers), a
 frame is iconized when its parent is iconized.
 
 If @racket[parent] is @racket[#f], then the eventspace for the
@@ -72,14 +67,6 @@ some platforms:
  @item{@racket['no-system-menu] --- omits the system menu
  (Windows)}
 
- @item{@racket['mdi-child] --- creates the frame as a MDI
- (multiple document interface) child frame, mutually exclusive with
- @racket['mdi-parent] (Windows)}
-
- @item{@racket['mdi-parent] --- creates the frame as a MDI
- (multiple document interface) parent frame, mutually exclusive with
- @racket['mdi-child] (Windows)}
-
  @item{@racket['toolbar-button] --- includes a toolbar button on the
  frame's title bar (Mac OS X); a click on the toolbar button triggers
  a call to @method[frame% on-toolbar-button-click]}
@@ -99,9 +86,6 @@ some platforms:
 
 ]
 
-If the @racket['mdi-child] style is specified, the @racket[parent] must be
- a frame with the @racket['mdi-parent] style, otherwise @|MismatchExn|.
-
 Even if the frame is not shown, a few notification events may be
  queued for the frame on creation. Consequently, the new frame's
  resources (e.g., memory) cannot be reclaimed until some events are
@@ -199,22 +183,6 @@ Gets or sets the frame's modification state as reflected to the user.
 
 }
 
-@defmethod[(on-mdi-activate [active? any/c])
-           void?]{
-
-Called on Windows when a MDI-child frame becomes the active frame
- within its parent (in which case the argument is @racket[#t]), or when
- the child frame ceases to be the active frame (in which case the
- argument is @racket[#f]).
-
-
-MDI activation is different from keyboard-focus activation. If the
- parent frame is the frontmost top-level frame, so that the MDI child
- gets or loses the keyboard focus, then a separate
-@method[top-level-window<%> on-activate] notification is sent to the MDI-child frame.
-
-}
-
 @defmethod[(on-menu-char [event (is-a?/c key-event%)])
            boolean?]{
 
diff --git a/doc/release-notes/racket/Draw_and_GUI_5_1.txt b/doc/release-notes/racket/Draw_and_GUI_5_1.txt
index 1c8aef3cf8..0621180eda 100644
--- a/doc/release-notes/racket/Draw_and_GUI_5_1.txt
+++ b/doc/release-notes/racket/Draw_and_GUI_5_1.txt
@@ -18,8 +18,8 @@ API:
 
    The GRacket executable still offers some additional GUI-specific
    functionality however. Most notably, GRacket is a GUI application
-   under Windows (as opposed to a console application, which is
-   launched slightly differently by the OS), GRacket is a bundle under
+   on Windows (as opposed to a console application, which is
+   launched slightly differently by the OS), GRacket is a bundle on
    Mac OS X (so the dock icon is the Racket logo, for example), and
    GRacket manages single-instance mode for Windows and X.
 
@@ -167,6 +167,11 @@ are somewhat more restricted in the actions they can take without
 disabling the control's handling of key and mouse events. See the
 documentation for more information.
 
+The 'mdi-child and 'mdi-parent styles for `frame%' on Windows are no
+longer supported, and the `on-mdi-activate' method has been
+removed. (The styles and method actually lingered in `racket/gui'
+until version 5.1.2.3, but they did not work.)
+
 
 Registry Functions
 -----------------
diff --git a/doc/release-notes/racket/HISTORY.txt b/doc/release-notes/racket/HISTORY.txt
index 4548813389..d65447f4f4 100644
--- a/doc/release-notes/racket/HISTORY.txt
+++ b/doc/release-notes/racket/HISTORY.txt
@@ -1,6 +1,7 @@
 Version 5.1.2.3
 Added set-port-next-location! and changed the default prompt 
  read handler to use it when input and output ar terminals
+racket/gui: removed unsupported MDI styles and method
 
 Version 5.1.2.2
 Changed the location-creation semantics of internal definitions