BACKGROUND: During 98 several strategies have been implemented to increase the prescription of efficient (ED) and generic (GD) drugs. In Catalonia to improve the generics’ use, economic incentives have been offered to some Primary Care Teams. Although the general practitioners (GP) in our study were not included in this incentive’s project, they received the intervention presented in this study. OBJECTIVE: To evaluate an intervention to implement ED and GD in a Primary Care District in Barcelona. METHODS Type of study: Pre-post intervention with control group. Setting and period: Drug prescription follow up of the primary care district (296.000 inhabitants) and Catalonia (control group) during 97, 98 and January-March 99. Information source: Catalan Institut of Health’s pharmaceutical computerised system. Intervention: Design of a sheet of paper with information about 1) prices of different drugs for a same active principle, including those drugs responsible for higher pharmaceutical cost and with ED 2) all generic drugs on the market and how to prescribe them. In January 98, it was distributed to all GP. Variables: Number and price of the drugs of 18 active principle and savings obtained. RESULTS: The savings obtained prescribing ED of omeprazole, enalapril and nimodipino during the period 99-97 have increased a 182% in the district versus 103% in Catalonia. The % of GD is also greater in our district: Ranitidina 24% vs. 14%, Captopril 13,2% vs. 8,6%, Aciclovir 14,8% vs. 11.8%; Alprazolam 8.2% vs. 5% Fluoxetina 3,73% vs. 2,7%. During January-March 99, our district saved 69 millions (pesetas), 90% by prescribing ED and 10% by generics. CONCLUSION: The GP collaboration and an instrument with updated information and easy to use have allowed to achieve a higher percentage of ED and GD prescription in our district. To rationalise drug ‘s prescription, it is necessary to take into account the ED.