This study examined whether deep brain stimulation (DBS) would affect the contrast sensitivity (CS) curve in patients with PD. CS was tested in 12 nondemented PD patients treated with bilateral subthalamic nucleus DBS on and off stimulation and medications. Neither stimulation condition (on vs. off) nor medications altered CS performance in this group of patients. However, collapsed across conditions, patients with bipolar stimulation in this study had significantly poorer CS at higher spatial frequencies (12 and 18 cycles per degree) than patients with monopolar stimulation. This suggests that CS deficits in PD may possibly be influenced by DBS polarity and merits further study.