I have a DataGridView that contains one ComboBox column. the datagridview gets data from a table. the combo box has datasource from another table that contains two columns, one is ID and the another is name. I set the ID field as the combobox valuemember and set the name field as the conbo box dispalymember. everything works fine. the problem is that if a cell originally is blank. I select a value from combo box for the sell, then I find I made amistake and want to undo it. it cannot change the cell back to blank. Anyway can we do this. please help. Thanks.