OBJECTIVE: To evaluate the NHS consumption evolution for non selective Cox2 inhibitors (NSAID) and Drugs for Acid Related Disorders (DARD) after the reimbursement of rofecoxib and celecoxib. The substances considered were: NSAID: aceclofenac, acemetacin, diclofenac, ibuprofen, indometacin, meloxicam, nabumeton, naproxen, nimesulide, piroxicam, tenoxicam; Proton Pump Inhibitors: omeprazol, pantoprazol, lansoprazol ,rabeprazol, esomeprazol; H2 Receptor Antagonists: cimetidine, famotidine, nizatidine, ranitidine; misoprolol and sucralfate were also studied. METHODS: Using data of reimbursed medicines dispensed in the NHS (in DDD units) from January 1995 to June 2001, modelling was performed using SARIMA models. Intervention variables were used to evaluate the influence of the reimbursement of Cox2 inhibitors on overall NSAID and DARD consumption. RESULTS: NSAID overall consumption increased for the considered time period from 50.49 DDD/1.000 inhabitants/day in year 2000 to 62.35 DDD/1.000 inhabitants /day 1º semester 2001. DARD consumption also increased from 24.87 DDD/1.000 inhabitants/day to 28 DDD/1.000 inhabitants /day during the above mentioned period of time. CONCLUSIONS: The global dispensing of selected NSAID in 1º semester 2001 faced a total increase above the projected value. The Cox2 inhibitors appear to have an add-on effect, rather than a substitutive effect on already existing therapies. Moreover we did not observe decrease on DARD consumption patterns.