Single cell activity of the basal ganglia, and the pallidal segments (GPe and GPi) in particular, has been well-characterized during deep brain stimulation (DBS) surgeries in unmedicated (“OFF state”) patients with Parkinson’s disease (PD). However, little is known about the effects dopaminergic medicine has on the individual cells’ activity in these structures. Here, we compared single cell recordings of the GPe and GPi of two medicated patients (“ON state”) with three patients in the OFF state. All patients suffered from late stage mixed PD. For the analysis, the neurons recorded during DBS implantation surgeries were divided into three groups, according to their activity type – into tonic, burst and pause cells - using a hierarchical clustering method based on Ward’s algorithm. We found that the GPi had lesser firing rate and higher pause index values (p<0.05 by Mann-Whitney U test) under the medication. Moreover, the proportion of tonic neurons in it was significantly lower in the ON state, while accompanied by increased proportion of pause neurons. Intriguingly, there were no differences in either the overall activity or proportions of different cell types in the GPe between the states. Our observations are in line with the idea that GPi turns hyperactive in PD, and the medication reduces this hyperactivity. Results regarding the GPe require further investigation, as the role it plays in the basal ganglia interaction seems to be more complicated than it was believed. The study was funded by the Russian Science Foundation (23-15-00487).