It's a nested property you need. The DefaultCellStyle property of the grid is type DataGridViewCellStyle. That class is used in various places to set various style-related properties of cells and, in this case, it is the default style for every cell in the grid. The BackColor property of that type determines the BackColor of affected cells. In this case, it's set to SystemColors.Window by default so, if you're seeing grey, either you must have already set the property or else your system theme uses grey for windows. You can change it in the designer via the properties window and a dialogue, or you can change it in code. If you do it in code, I think that it will only affect cells created after the change.