Prescription information leaflets (PILs) for penicillins, diuretics and benzodiazepines were evaluated in a small Hampshire town. A second town, in which no leaflets were distributed, acted as a control. Knowledge about these medicines was greater amongst the 252 patients who received leaflets compared with 247 controls. Significantly more patients who received leaflets knew the potential side-effects of their treatment and, with the exception of those taking penicillins, were more satisfied with the information they received. These findings add further support for the routine use of PILs in general practice.