Try this.In my ex.both datasets contain one field each.For multiple fields you have to change code a bit.



foreach (DataRow row in ds.Tables[0].Rows)
{
foreach (DataRow row1 in ds1.Tables[0].Rows)
{
if (row != row1)
{
if (ListBox1.Items.Count == 0)
{
ListBox1.Items.Add(new ListItem(row.ItemArray.GetValue(0).ToString()));
}
else
{
for (int i = 0; i < ListBox1.Items.Count; i++)
{



if (row.ItemArray.GetValue(0).ToString() != ListBox1.Items[i].Value)
if (i == ListBox1.Items.Count - 1)
{ ListBox1.Items.Add(new ListItem(row.ItemArray.GetValue(0).ToString())); }




}
}

}
}
}