procedure TForm1.Button1Click(Sender: TObject);
var
 Document: IHTMLDocument2;
 rbTestList: IHTMLElementCollection;
 rbTest: IHTMLOptionButtonElement;
 I: Integer;
begin
 // Get a reference to the document
 Document := WebBrowser1.Document as IHTMLDocument2;
 // Get a reference to input-control (Radiobutton)
 rbTestList := Document.all.item('rating', EmptyParam) as IHTMLElementCollection;
 // Get current values.
 for I := 0 to rbTestList.Length - 1 do
 begin
  // reference to the i. RadioButton
  rbTest := rbTestList.item(I, EmptyParam) as IHTMLOptionButtonElement;
  // Show a message if radiobutton is checked
  if rbTest.Checked then
  ShowMessageFmt('Der RadioButton mit dem Wert %s' +
  ' ist ausgewahlt!', [rbTest.Value]);
 end;
 // Set new values
 for I := 0 to rbTestList.Length - 1 do
 begin
  // reference to the i. RadioButton
  rbTest := rbTestList.item(I, EmptyParam) as IHTMLOptionButtonElement;
  // check radiobutton with value 3.
  if rbTest.Value = '3' then
  rbTest.Checked := True;
 end;
end;