diff --git a/basis/zlib/authors.txt b/basis/zlib/authors.txt
new file mode 100755
index 0000000000..7c1b2f2279
--- /dev/null
+++ b/basis/zlib/authors.txt
@@ -0,0 +1 @@
+Doug Coleman
diff --git a/basis/zlib/ffi/authors.txt b/basis/zlib/ffi/authors.txt
new file mode 100755
index 0000000000..7c1b2f2279
--- /dev/null
+++ b/basis/zlib/ffi/authors.txt
@@ -0,0 +1 @@
+Doug Coleman
diff --git a/basis/zlib/ffi/ffi.factor b/basis/zlib/ffi/ffi.factor
new file mode 100755
index 0000000000..bda2809f56
--- /dev/null
+++ b/basis/zlib/ffi/ffi.factor
@@ -0,0 +1,30 @@
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: alien alien.syntax combinators system ;
+IN: zlib.ffi
+
+<< "zlib" {
+    { [ os winnt? ] [ "zlib1.dll" ] }
+    { [ os macosx? ] [ "libz.dylib" ] }
+    { [ os unix? ] [ "libz.so" ] }
+} cond "cdecl" add-library >>
+
+LIBRARY: zlib
+
+CONSTANT: Z_OK 0
+CONSTANT: Z_STREAM_END 1
+CONSTANT: Z_NEED_DICT 2
+CONSTANT: Z_ERRNO -1
+CONSTANT: Z_STREAM_ERROR -2
+CONSTANT: Z_DATA_ERROR -3
+CONSTANT: Z_MEM_ERROR -4
+CONSTANT: Z_BUF_ERROR -5
+CONSTANT: Z_VERSION_ERROR -6
+
+TYPEDEF: void Bytef
+TYPEDEF: ulong uLongf
+TYPEDEF: ulong uLong
+
+FUNCTION: int compress ( Bytef* dest, uLongf* destLen, Bytef* source, uLong sourceLen ) ;
+FUNCTION: int compress2 ( Bytef* dest, uLongf* destLen, Bytef* source, uLong sourceLen, int level ) ;
+FUNCTION: int uncompress ( Bytef* dest, uLongf* destLen, Bytef* source, uLong sourceLen ) ;
diff --git a/basis/zlib/zlib-tests.factor b/basis/zlib/zlib-tests.factor
new file mode 100755
index 0000000000..0ac77277dc
--- /dev/null
+++ b/basis/zlib/zlib-tests.factor
@@ -0,0 +1,9 @@
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: kernel tools.test zlib classes ;
+IN: zlib.tests
+
+: compress-me ( -- byte-array ) B{ 1 2 3 4 5 } ;
+
+[ t ] [ compress-me [ compress uncompress ] keep = ] unit-test
+[ t ] [ compress-me compress compressed instance? ] unit-test
diff --git a/basis/zlib/zlib.factor b/basis/zlib/zlib.factor
new file mode 100755
index 0000000000..b40d9c2a98
--- /dev/null
+++ b/basis/zlib/zlib.factor
@@ -0,0 +1,48 @@
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: alien alien.c-types alien.syntax byte-arrays combinators
+kernel math math.functions sequences system accessors
+libc ;
+QUALIFIED: zlib.ffi
+IN: zlib
+
+TUPLE: compressed data length ;
+
+: <compressed> ( data length -- compressed )
+    compressed new
+        swap >>length
+        swap >>data ;
+
+ERROR: zlib-failed n string ;
+
+: zlib-error-message ( n -- * )
+    dup zlib.ffi:Z_ERRNO = [
+        drop errno "native libc error"
+    ] [
+        dup {
+            "no error" "libc_error"
+            "stream error" "data error"
+            "memory error" "buffer error" "zlib version error"
+        } ?nth
+    ] if zlib-failed ;
+
+: zlib-error ( n -- )
+    dup zlib.ffi:Z_OK = [ drop ] [ dup zlib-error-message zlib-failed ] if ;
+
+: compressed-size ( byte-array -- n )
+    length 1001/1000 * ceiling 12 + ;
+
+: compress ( byte-array -- compressed )
+    [
+        [ compressed-size <byte-array> dup length <ulong> ] keep [
+            dup length zlib.ffi:compress zlib-error
+        ] 3keep drop *ulong head
+    ] keep length <compressed> ;
+
+: uncompress ( compressed -- byte-array )
+    [
+        length>> [ <byte-array> ] keep <ulong> 2dup
+    ] [
+        data>> dup length
+        zlib.ffi:uncompress zlib-error
+    ] bi *ulong head ;