Drug use in Italy in the period 1983-1991 has been analysed. The twenty most used substances accounted for about 20% of the sold packages. The effect of marketing of new drugs is worth noting: new and more expensive drugs are preferred even when effective, safe and less expensive alternatives are available. Prescribers have to face a highly dynamic pharmaceutical market in which 30% of substances (among the 300 most sold) changes every five years. Other than a more rational formulary, independent information and continuing education have to be considered as tools to improve a more rational prescribing.