diff --git a/extra/peg/replace/replace-docs.factor b/extra/peg/replace/replace-docs.factor
new file mode 100644
index 0000000000..35f13e8ecd
--- /dev/null
+++ b/extra/peg/replace/replace-docs.factor
@@ -0,0 +1,43 @@
+! Copyright (C) 2006 Chris Double.
+! See http://factorcode.org/license.txt for BSD license.
+USING: help.syntax help.markup peg peg.replace ;
+
+HELP: tree-write
+{ $values 
+  { "object" "an object" } }
+{ $description 
+    "Write the object to the standard output stream, unless "
+    "it is an array, in which case recurse through the array "
+    "writing each object to the stream." }
+{ $example "{ 65 \"bc\" { 68 \"ef\" } } tree-write" "AbcDef" } ;
+
+HELP: search
+{ $values 
+  { "string" "a string" } 
+  { "parser" "a peg based parser" } 
+  { "seq"    "a sequence" } 
+}
+{ $description 
+    "Returns a sequence containing the parse results of all substrings "
+    "from the input string that successfully parse using the "
+    "parser."
+}
+    
+{ $example "\"one 123 two 456\" 'integer' search" "V{ 123 456 }" }
+{ $example "\"one 123 \\\"hello\\\" two 456\" 'integer' 'string' 2array choice search" "V{ 123 \"hello\" 456 }" }
+{ $see-also replace } ;
+    
+HELP: replace
+{ $values 
+  { "string" "a string" } 
+  { "parser" "a peg based parser" } 
+  { "result"    "a string" } 
+}
+{ $description 
+    "Returns a copy of the original string but with all substrings that "
+    "successfully parse with the given parser replaced with "
+    "the result of that parser."
+}   
+{ $example "\"one 123 two 456\" 'integer' [ 2 * number>string ] action replace" "\"one 246 two 912\"" }
+{ $see-also search } ;
+
diff --git a/extra/peg/replace/replace-tests.factor b/extra/peg/replace/replace-tests.factor
new file mode 100644
index 0000000000..91c91f4fc4
--- /dev/null
+++ b/extra/peg/replace/replace-tests.factor
@@ -0,0 +1,18 @@
+! Copyright (C) 2007 Chris Double.
+! See http://factorcode.org/license.txt for BSD license.
+!
+USING: kernel math math.parser arrays tools.test peg peg.replace ;
+IN: temporary
+
+{ V{ 123 456 } } [
+  "abc 123 def 456" 'integer' search  
+] unit-test
+
+{ V{ 123 "hello" 456 } } [
+  "one 123 \"hello\" two 456" 'integer' 'string' 2array choice search  
+] unit-test
+
+{ "abc 246 def 912" } [
+  "abc 123 def 456" 'integer' [ 2 * number>string ] action replace  
+] unit-test
+
diff --git a/extra/peg/replace/replace.factor b/extra/peg/replace/replace.factor
new file mode 100755
index 0000000000..5440a8e45f
--- /dev/null
+++ b/extra/peg/replace/replace.factor
@@ -0,0 +1,32 @@
+! Copyright (C) 2006 Chris Double.
+! See http://factorcode.org/license.txt for BSD license.
+USING: kernel math io io.streams.string sequences strings
+combinators peg memoize arrays ;
+IN: peg.replace 
+
+: tree-write ( object -- )
+  { 
+    { [ dup number?   ] [ write1 ] }
+    { [ dup string?   ] [ write ] }
+    { [ dup sequence? ] [ [ tree-write ] each ] }
+    { [ t             ] [ write ] }
+  } cond ;
+
+MEMO: any-char-parser ( -- parser )
+  [ drop t ] satisfy ;
+
+: search ( string parser -- seq )
+  any-char-parser [ drop f ] action 2array choice repeat0 parse dup [
+    parse-result-ast [ ] subset 
+  ] [
+    drop { }
+  ] if ;
+
+
+: (replace) ( string parser -- seq )
+  any-char-parser 2array choice repeat0 parse parse-result-ast [ ] subset ;
+
+: replace ( string parser -- result )
+ [  (replace) [ tree-write ] each ] string-out ;
+
+