Background: Subthalamic nucleus deep brain stimulation (STN DBS) improves motor symptoms of Parkinson’s disease (PD). However, it is argued whether it may alter frontal lobe functions, which we studied using the antisaccade (AS) task as well as neuropsychological tests. Objectives: To investigate effects of STN DBS on frontal lobe functions and AS performance in PD. Methods: Twenty-nine PD patients (HY II-III, age 58.5±7.9, 13 men, 16 women) with STN DBS. Subjects performed AS when DBS was on and off. They also underwent neuropsychological batteries, i.e. “Kanahiroi” multi-cancellation test and the verbal fluency test (VFT) before and after DBS surgery. Results: (1) The scores of “Kanahiroi” test and VFT did not change from pre- to post-surgery. (2) STN DBS improved the latency and accuracy of AS. The frequency of directional errors (prosaccades) was unchanged by STN DBS. (3) No correlations were found between the saccade parameters, such as latency, accuracy, and frequency of prosaccades, and scores of the “Kanahiroi” test or of VFT. Discussion: DBS surgery did not affect scores of the “Kanahiroi” test or VFT. In contrast, STN DBS improved AS performances. This suggests that neuropsychological tests and AS performance reflect distinct aspects of frontal lobe functions.