The antisaccade task has been used widely to assess a frontal lobe deficit. In the present study cortical potentials preceding prosaccades and antisaccades were recorded in 7 healthy subjects with 19 scalp electrodes according to the international 10-20 system. The main results were as follows: (1) In both saccade types, a slow presaccadic negative shift was observed at dorso-medial frontal recording sites. The integral over these potentials was significantly greater for antisaccades at the C3, C4 and Cz location than in prosaccades. (2) The integral over presaccadic positivity was significantly lower for antisaccades compared with prosaccades at the Cz location. It is concluded that these results support an important role of the supplementary eye fields in generating antisaccades.