OBJECTIVES: To assess the quality of prescription of fluoroquinolons, aminosids and amoxicillin-clavulanic acids in medicine departments. METHODS: Data on target antibiotic prescription were collected on a given day and confronted to local recommendations and literature guidelines. Evaluation of antibiotic therapy was done by assessing molecule choice, administration conditions (dosages, route and administration schedule, treatment duration), reassessment of treatments 48-72 h later, dose adaptation of aminosids depending on serum monitoring. RESULTS: Sixty-three patients were included and 67 "target" antibiotics were prescribed. Prevalence of antibiotic-treated patients was 24.4%, and 14.6% for "target" antibiotic-treated patients. Antibiotic choice was appropriate in 67% of prescriptions. Dosages were adequates in 94% of case and administration schedule in 97% of cases. The oral route administration as soon as possible was applied to half of patients. Treatment duration were respected for 94% of prescriptions. Reassessment of antibiotic therapy 48-72 h later was realized in 66% of cases. Dose adaptation of aminosids, when necessary, was realized on one third of cases. For all the quality criteria assessed, the overall frequency of prescription conformity was 44%. CONCLUSION: Large diffusion of protocols, systematic reassessment of treatments at 48-72 h, promotion of training sessions for new prescribers in the institution, reinforcing the function of medical correspondents in antibiotic therapy and infectiologists, periodic evaluation of antibiotic therapy, should improve the quality of antibiotic therapy.