// Recursive procedure to build a list of files
procedure FindFiles(FilesList: TStringList; StartDir, FileMask: string);
var
  SR: TSearchRec;
  DirList: TStringList;
  IsFound: Boolean;
  i: integer;
begin
  if StartDir[length(StartDir)] <> '\' then
    StartDir := StartDir + '\';
 
  { Build a list of the files in directory StartDir
     (not the directories!)                         }
 
  IsFound :=
    FindFirst(StartDir+FileMask, faAnyFile-faDirectory, SR) = 0;
  while IsFound do begin
    FilesList.Add(StartDir + SR.Name);
    IsFound := FindNext(SR) = 0;
  end;
  FindClose(SR);
 
  // Build a list of subdirectories
  DirList := TStringList.Create;
  IsFound := FindFirst(StartDir+'*.*', faAnyFile, SR) = 0;
  while IsFound do begin
    if ((SR.Attr and faDirectory) <> 0) and
         (SR.Name[1] <> '.') then
      DirList.Add(StartDir + SR.Name);
    IsFound := FindNext(SR) = 0;
  end;
  FindClose(SR);
 
  // Scan the list of subdirectories
  for i := 0 to DirList.Count - 1 do
    FindFiles(FilesList, DirList[i], FileMask);
 
  DirList.Free;
end;
 
// Example: how to use FindFiles
procedure TForm1.ButtonFindClick(Sender: TObject);
var
  FilesList: TStringList;
begin
  FilesList := TStringList.Create;
  try
    FindFiles(FilesList, EditStartDir.Text, EditFileMask.Text);
    ListBox1.Items.Assign(FilesList);
    LabelCount.Caption := 'Files found: ' + IntToStr(FilesList.Count);
  finally 
    FilesList.Free;
  end;
end;