[lmikle]

Да, вот так работает:

Код:

uses
  ZLib;

procedure TForm1.Button1Click(Sender: TObject);
var
  AStream : TFileStream;
  AZLib : TCompressionStream;
  AMemStream : TMemoryStream;
  ALen : Int64;
begin
  AStream := TFileStream.Create('c:\test.z',fmCreate);
  AMemStream := TMemoryStream.Create;
  AZLib := TCompressionStream.Create(clMax,AStream);
  Try
    Memo1.Lines.SaveToStream(AMemStream);
    AMemStream.Seek(0,0);
    ALen := AMemStream.Size;
    AZLib.WriteBuffer(ALen,SizeOf(Int64));
    AZLib.CopyFrom(AMemStream,ALen);
  Finally
    AZLib.Free;
    AStream.Free;
  End;
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  AZLib : TDecompressionStream;
  AStream : TFileStream;
  AMemStream : TMemoryStream;
  ALen : Int64;
begin
  AStream := TFileStream.Create('c:\test.z',fmOpenRead);
  AZLib := TDecompressionStream.Create(AStream);
  AMemStream := TMemoryStream.Create;
  Try
    AZLib.ReadBuffer(ALen,SizeOf(Int64));
    AMemStream.CopyFrom(AZLib,ALen);
    AMemStream.Seek(0,0);
    Memo1.Lines.LoadFromStream(AMemStream);
  Finally
    AMemStream.Free;
    AZLib.Free;
    AStream.Free;
  End;
end;