<script type="text/javascript">
function CheckVisible(ElementValue)
		{
		    alert(ElementValue);
			if(ElementValue == 'Check')
			{
				document.getElementById('divACH').style.display = 'block';
			} else
			{
				document.getElementById('divACH').style.display = 'none';
			}
			return true;
		}
</script>
<select runat="server" id="ee" onchange="CheckVisible(this.value)">
<option> 1 </option>
<option>Check</option>
<option> 3 </option>
</select>
<div id="divACH">dfdfd</div>