<script language="javascript"> function check(){ s.disabled=(t1.value==""||t2.value==""||t3.value=="") } </script> <input name="t1" onpropertychange="check()" /> <input name="t2" onpropertychange="check()" /> <input name="t3" onpropertychange="check()" /> <input type="submit" name="s" disabled="desabled" />