This study assessed the effect of an educational intervention (interactive group discussion) on the prescribing behaviour of 51 general physicians from the north-west of Tabriz. Prescriptions were analysed pre-intervention and post-intervention (control and intervention groups) using a proforma with 8 indicators of correct prescribing. The mean number of drugs per prescription pre-intervention was 3.82. The percentage of prescriptions with antibiotics, corticosteroids and injections were 40.8%, 25.9% and 58.0%, respectively. Following the intervention there were slight but not significant changes in the indicators in both intervention and control groups compared with pre-intervention results.