SKF83959 is a dopamine D1 receptor partial agonist whose in vivo pharmacological effects have been previously tested mostly on reflexive motor behaviors in animals to examine its therapeutic potentials for Parkinson's disease. Little is known for the effects of SKF83959 on the conditioned behavior. The present study, thus, examined the effects of SKF83959 on an instrumental conditioned behavior in the rat which paradigm is known as useful to screen drugs in psychopharmacological profile. Male Wistar rats deprived of water were divided into two groups and trained for one month to lever-press for water (as the reinforcer) on a fixed-ratio 20 (FR-20) and a fixed-ratio 5 (FR-5) schedule, respectively. After reaching a stable performance level, the FR-20 rat emitted significantly more lever presses than the FR-5 rat. A dose-response test was conducted with SKF 83959 dosing given in the order of 0.0, 0.1, 0.01, and 1.0 mg/kg). The results showed that the 1.0 mg/kg of SKF 83959 significantly reduced lever pressing on either task. The subjects were then re-trained and given to another dose-response test of SKF83959 which drug was administered in a descending order (0.0, 1.0, 0.5, 0.25, and 0.1 mg/kg). The results showed the lever pressing on either task was significantly reduced throughout the dosing treatments. Using a model with the reduction of lever pressing by the 0.5 mg/kg of SKF83959, selective D1 and D2 receptor agonists (SKF38393 and quinpirole, respectively) were administered for a pharmacological interaction test. Neither SKF38393 nor quinpirole reversed the aforementioned behavioral impairment of SKF83959. These data, together our previous work, indicate that the degree of operant behavior disrupted by SKF83959 is depended upon the reinforcement schedule and the dosing regimen.