diff --git a/collects/racket/private/for.rkt b/collects/racket/private/for.rkt
index 585324b6b1..6b63210598 100644
--- a/collects/racket/private/for.rkt
+++ b/collects/racket/private/for.rkt
@@ -29,6 +29,7 @@
              (rename *in-range in-range)
              (rename *in-naturals in-naturals)
              (rename *in-list in-list)
+             (rename *in-mlist in-mlist)
              (rename *in-vector in-vector)
              (rename *in-string in-string)
              (rename *in-bytes in-bytes)
@@ -318,6 +319,7 @@
   (define (sequence? v)
     (or (do-sequence? v)
         (list? v)
+        (mpair? v)
         (vector? v)
         (string? v)
         (bytes? v)
@@ -329,6 +331,7 @@
     (cond
       [(do-sequence? v) ((do-sequence-ref v 0))]
       [(list? v) (:list-gen v)]
+      [(mpair? v) (:mlist-gen v)]
       [(vector? v) (:vector-gen v 0 (vector-length v) 1)]
       [(string? v) (:string-gen v 0 (string-length v) 1)]
       [(bytes? v) (:bytes-gen v 0 (bytes-length v) 1)]
@@ -378,9 +381,15 @@
   (define (in-list l)
     ;; (unless (list? l) (raise-type-error 'in-list "list" l))
     (make-do-sequence (lambda () (:list-gen l))))
-
+  
   (define (:list-gen l)
     (values car cdr l pair? void void))
+  
+  (define (in-mlist l)
+    (make-do-sequence (lambda () (:mlist-gen l))))
+
+  (define (:mlist-gen l)
+    (values mcar mcdr l mpair? void void))
 
   (define (check-ranges who start stop step)
     (unless (exact-nonnegative-integer? start) (raise-type-error who "exact non-negative integer" start))
@@ -1073,6 +1082,31 @@
              ;; loop args -- ok to use unsafe-cdr, since car passed
              ((unsafe-cdr lst)))]]
         [_ #f])))
+  
+  (define-sequence-syntax *in-mlist
+    (lambda () #'in-mlist)
+    (lambda (stx)
+      (syntax-case stx ()
+        [[(id) (_ lst-expr)]
+         #'[(id)
+            (:do-in
+             ;;outer bindings
+             ([(lst) lst-expr])
+             ;; outer check
+             (void) ; (unless (list? lst) (in-list lst))
+             ;; loop bindings
+             ([lst lst])
+             ;; pos check
+             (not (null? lst))
+             ;; inner bindings
+             ([(id) (mcar lst)])
+             ;; pre guard
+             #t
+             ;; post guard
+             #t
+             ;; loop args 
+             ((mcdr lst)))]]
+        [_ #f])))
 
   (define-for-syntax (vector-like-gen vector?-id
                                       unsafe-vector-length-id
diff --git a/collects/scribblings/reference/dicts.scrbl b/collects/scribblings/reference/dicts.scrbl
index adf4ec4093..a96761a276 100644
--- a/collects/scribblings/reference/dicts.scrbl
+++ b/collects/scribblings/reference/dicts.scrbl
@@ -24,6 +24,10 @@ values. The following datatypes are all dictionaries:
 
 ]
 
+A dictionary can be used as a two-valued sequence (see
+@secref["sequences"]). The associations of the dictionary serve as elements
+of the sequence. See also @scheme[in-dict], @scheme[in-dict-keys], and @scheme[in-dict-values].
+
 @note-lib[racket/dict]
 
 @defproc[(dict? [v any/c]) boolean?]{
diff --git a/collects/scribblings/reference/mpairs.scrbl b/collects/scribblings/reference/mpairs.scrbl
index 84932339ac..8f879b5885 100644
--- a/collects/scribblings/reference/mpairs.scrbl
+++ b/collects/scribblings/reference/mpairs.scrbl
@@ -20,6 +20,10 @@ list. Instead of programming with mutable pairs and mutable lists,
 data structures such as pairs, lists, and hash tables are practically
 always better choices.
 
+A @tech{mutable list} can be used as a single-valued sequence (see
+@secref["sequences"]). The elements of the @tech{mutable list} serve as elements
+of the sequence. See also @scheme[in-mlist].
+
 @; ----------------------------------------
 @section{Mutable Pair Constructors and Selectors}
 
diff --git a/collects/scribblings/reference/sequences.scrbl b/collects/scribblings/reference/sequences.scrbl
index 27a159e00c..fadbd178dd 100644
--- a/collects/scribblings/reference/sequences.scrbl
+++ b/collects/scribblings/reference/sequences.scrbl
@@ -2,7 +2,8 @@
 @(require "mz.ss"
           (for-syntax racket/base)
           scribble/scheme
-	  (for-label racket/generator))
+	  (for-label racket/generator
+                     racket/mpair))
 
 @(define generator-eval
    (lambda ()
@@ -27,15 +28,21 @@ built-in datatypes, the sequence datatype includes the following:
 
 @itemize[
 
+ @item{strings (see @secref["strings"])}
+           
+ @item{byte strings (see @secref["bytestrings"])}
+
  @item{lists (see @secref["pairs"])}
 
+ @item{mutable lists (see @secref["mpairs"])}
+
  @item{vectors (see @secref["vectors"])}
 
  @item{hash tables (see @secref["hashtables"])}
 
- @item{strings (see @secref["strings"])}
+ @item{dictionaries (see @secref["dicts"])}
 
- @item{byte strings (see @secref["bytestrings"])}
+ @item{sets (see @secref["sets"])}
 
  @item{input ports (see @secref["ports"])}
 
@@ -167,6 +174,11 @@ Returns a sequence equivalent to @scheme[lst].
 @info-on-seq["pairs" "lists"]
 @speed[in-list "list"]}
 
+@defproc[(in-mlist [mlst mlist?]) sequence?]{
+Returns a sequence equivalent to @scheme[mlst].
+@info-on-seq["mpairs" "mutable lists"]
+@speed[in-mlist "mutable list"]}
+
 @defproc[(in-vector [vec vector?]
                     [start exact-nonnegative-integer? 0] 
                     [stop (or/c exact-nonnegative-integer? #f) #f] 
diff --git a/collects/scribblings/reference/sets.scrbl b/collects/scribblings/reference/sets.scrbl
index 358ca31364..282debdbe1 100644
--- a/collects/scribblings/reference/sets.scrbl
+++ b/collects/scribblings/reference/sets.scrbl
@@ -8,14 +8,16 @@ A @deftech{set} represents a set of distinct elements. For a given
 set, elements are equivalent via @scheme[equal?], @scheme[eqv?], or
 @scheme[eq?]. Two sets are @scheme[equal?] when they use the same
 element-comparison procedure (@scheme[equal?], @scheme[eqv?], or
-@scheme[eq?]) and have equivalent elements. A set can be used as a
-@tech{sequence} (see @secref["sequences"]).
+@scheme[eq?]) and have equivalent elements.
+
+A set can be used as a single-valued sequence (see
+@secref["sequences"]). The elements of the set serve as elements
+of the sequence. See also @scheme[in-set].
 
 Operations on sets that contain elements that are mutated are
 unpredictable in much the same way that @tech{hash table} operations are
 unpredictable when keys are mutated.
 
-
 @note-lib[racket/set]
 
 @defproc[(set? [v any/c]) boolean?]{
diff --git a/collects/tests/racket/for.rktl b/collects/tests/racket/for.rktl
index db1c46c3e0..675b9724ff 100644
--- a/collects/tests/racket/for.rktl
+++ b/collects/tests/racket/for.rktl
@@ -3,7 +3,8 @@
 
 (Section 'for)
 
-(require scheme/generator)
+(require scheme/generator
+         racket/mpair)
 
 (define-syntax (test-multi-generator stx)
   (syntax-case stx ()
@@ -105,6 +106,8 @@
 
 (test-generator [(a b c)] '(a b c))
 (test-generator [(a b c)] (in-list '(a b c)))
+(test-generator [(a b c)] (mlist 'a 'b 'c))
+(test-generator [(a b c)] (in-mlist (mlist 'a 'b 'c)))
 (test-generator [(a b c)] #(a b c))
 (test-generator [(a b c)] (in-vector #(a b c)))
 (test-generator [(b c d)] (in-vector #(a b c d) 1))