[Страдалецъ]

Код:

type
  TForm2 = class(TForm)
    ListBox1: TListBox;
    Edit1: TEdit;
    procedure FormCreate(Sender: TObject);
    procedure Edit1Change(Sender: TObject);
  private
    Backup: TStringList;
  public
    { Public declarations }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Edit1Change(Sender: TObject);
var
  i: Integer;
begin
 ListBox1.Items.BeginUpdate;
 ListBox1.Items.Assign(Backup);
 if Edit1.Text <> ''
 then for i := ListBox1.Count - 1 downto 0
      do if Pos(AnsiUpperCase(Edit1.Text), AnsiUpperCase(ListBox1.Items.Strings[i])) = 0
         then ListBox1.Items.Delete(i);
 ListBox1.Items.EndUpdate;
end;

procedure TForm2.FormCreate(Sender: TObject);
const
  Alpha: String = 'абвгдежзиклмнопрстуфхшэюя';
var
  i: Integer;
begin
 for i := 0 to 99
 do ListBox1.Items.Add(Alpha[1+Random(25)] + IntToStr(1 + Random(999)) +
                       Alpha[1+Random(25)] + Alpha[1+Random(25)] + IntToStr(1 + Random(199)));
 Backup := TStringList.Create;
 Backup.Assign(ListBox1.Items);
end;