OBJECTIVES: The purpose of this study was to analyze the impact of an inspector's stamp approval policy into the atypical antipsychotic market which was approved in 2003 in Andalusia –Spanish Region- and in 2004 in the rest of Spain. METHODS: The antipsychotic market in Spain, defined as the number of units sold, was described before and after the policy implementation (2003 and 2005). Data was collected from IMS database. Chi-squared analysis was used to contrast the atypical antipsychotic market in Andalusia in contrast with the rest of Spain before and after the policy implementation. Chi-squared analysis was also used for each leading product in the market of the atypical antipsychotics. Percentages of atypical and conventional antipsychotic sales in Andalusia were also compared in contrast with the rest of Spain for 2006 data. RESULTS: Sales grew constantly from 1996 –approval of the first atypical antipsychotics- to 2006 –after the policy implementation-. The patients treated with antipsychotics were mainly young adults, with no differences in prescription by gender. Andalusian sales proportion decreased for all main atypical antipsychotics –differences were significant-. In Andalusia the percentage of atypical antipsychotic sales over the total antipsychotics has also decreased since the policy was established. Atypical antipsychotics sales were 25,7% less in Andalusia than in the rest of Spain in 2006. Differences found for the main atypical antipsychotics were 68.5% for Quetiapine, 52.3% for Risperidone, 42.7% for Olanzapine and 25.2% for Sulpiride. CONCLUSION: Despite the general market growth, the impact of the inspector's stamp approval contributed to a decrease in atypical antipsychotic sales in Andalusia, meaning less pharmaceutical expenditure. It would be interesting to evaluate if, rationalising policies, apart from reducing the pharmaceutical expenditure, may cause an impact in the Andalusian population health.