i did't bound any datagrid to any datasource but i just added some rows to one datagrid and want to copy it to other form datagrid using the code RegistrationForm rg = new RegistrationForm(); for (int i = 0; i < dataGridView2.Rows.Count-1; i++) { string[] values = { dataGridView2.Rows[i].Cells ["TestID"].Value.ToString(), dataGridView2.Rows[i].Cells["TestName"].Value.ToString(), dataGridView2.Rows[i].Cells["Charges"].Value.ToString(), dataGridView2.Rows[i].Cells["DeliveryDate"].Value.ToString() }; RegistrationForm.dataGridView1.Rows.Add(values); his.Close();