<body>
<form id="form1" runat="server">
<div>
Select Country :<br />
<asp:dropdownlist id="DropDownList1" runat="server" autopostback="True" onselectedindexchanged="DropDownList1_SelectedIndexChanged" xmlns:asp="#unknown">
<asp:listitem>-Select-</asp:listitem>
<asp:listitem value="1">India</asp:listitem>
<asp:listitem value="2">Australia</asp:listitem>
</asp:dropdownlist>
<br />
Select State:<br />
<asp:dropdownlist id="DropDownList2" runat="server" xmlns:asp="#unknown">
</asp:dropdownlist>
</div>
</form>
</body>
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
string[] statelistIndia = new string[] {"-Select-","Maharashtra","New Delhi" };
string[] statelistAus = new string[] { "-Select-", "Victoria", "West Australia" };
if (DropDownList1.SelectedValue=="1")
{
DropDownList2.DataSource = statelistIndia;
DropDownList2.DataBind();
}
if (DropDownList1.SelectedValue == "2")
{
DropDownList2.DataSource = statelistAus;
DropDownList2.DataBind();
}
}