This code also shows how to progamatically clear then populate a combo box from client code.

Here is the code..

<!-- Author: Adrian Forbes -->
<%
    if Request("cboPrimary") = "" then
        lPrimary = "1"
    else
        lPrimary = Request("cboPrimary")
    end if
%>
<form name=frmTest action="TwoCombo.asp" method=POST>
<p>
<select name=cboPrimary size=1 onChange="frmTest.submit();">
<option value="1"<%if lPrimary = "1" then Response.Write " SELECTED"%>>Numbers
<option value="2"<%if lPrimary = "2" then Response.Write " SELECTED"%>>Fruit
<option value="3"<%if lPrimary = "3" then Response.Write " SELECTED"%>>Animals
</select>
</p>
<p>
<select name=cboSecondary size=1">
<%    select case lPrimary
    case "1"%>
<option value="1">One
<option value="2">Two
<option value="3">Three
    <%case "2"%>
<option value="4">Apple
<option value="5">Orange
<option value="6">Pear
    <%case "3"%>
<option value="4">Dog
<option value="5">Cat
<option value="6">Bear
    <%end select
%>
</select>
</form>