Recorrer DatagridView c#

private void button2_Click(object sender, EventArgs e)
{
    foreach (DataGridViewRow row in dataGridView1.Rows)
    {
         if (Convert.ToBoolean(row.Cells[1].Value))
         {
              // hacer algo
         }

      if (Convert.ToInt32(row.Cells[1].Value) == 1)
         {
              // what you want to do
         }

    }
}

Fuente: https://stackoverflow.com/questions/20452844/how-to-check-if-datagridview-checkbox-is-checked

saludos

Adalberto Montanía