An investigation of prescription and consumption of hypnotic and anxiolytic drugs in hospital was carried out and has associated a transverse prescription study and a prospective consumption study. The prescription study was undertaken on one day in several medical departments of Sainte-Marguerite Hospital in Marseille in February 1999. Of the 91 hospitalized patients included, 42 (46 per cent) had been prescribed a hypnotic or anxiolytic. Furthermore, the quantities of drugs taken out of the pharmacy during the month of February were 1.54 time more than those prescribed. This discrepancy was even more obvious in the case of certain benzodiazepines such as bromazepam (ratio from 1 to 4) and lorazepam (ratio from 1 to 8). Self-prescription and patients being supplied without a prescription are the hypotheses advanced to explain this phenomenon.