BACKGROUND: Pharmacists could dispense medicines without doctors' prescription in Korea before July 2000. The aim of this study was to compare the prescription behaviors of practicing doctors and pharmacists to arthritis by the simulated patients. We selected the arthritis as a subject of simulation because the arthritis was one of the major health problem and the abuse of corticosteroids might be prevalent in management of arthritis patients. METHODS: Seventy five private clinics and drug stores were selected in Seoul, Korea. The simulated patients were selected and trained standardized symptoms of arthritis. The simulated patients recorded the prescription behaviors of doctors and pharmacists. RESULTS: Mean number of prescribed medicines were 3.6 and 4.4 in clinic and drug store respectively. 16.2% of the clinics and 25.3% of the drug stores prescribed corticosteroids respectively with no significant difference. 45.3% of the pharmacists prescribed more than two kinds of anti inflammatory or analgesics and it was significantly higher than those of doctors. 65.3% of doctors intended to prescribe parenteral injection and 40% of the pharmacists performed some kinds of physical examination to the simulated patients. Both doctors and pharmacist gave little information or advice on use of medicines, possible side effects and past side effects of medicines. CONCLUSION: There were frequent abuse of corticosteroids and analgesics in private clinics and drug stores. Both doctors and pharmacists did not give enough information on use of medicines to the simulated patients.