OBJECTIVES: According to evidence from scientific literature the ease of administration, such as once-daily dosing, improves the adherence and persistance of patients with the pharmaceutical therapy. Adherence and persistance are key success factors in the treatment of schizophrenic patients, as drug discontinuation or non-adherence increase the risk of relapse, which eventually results in reduced quality adjusted life years and increased cost of care by more acute hospitalisation episodes. Our objective was to analyse the impact of once-daily dosing vs. twice daily dosing on the discontinuation rate of pharmaceutical therapy among patients with schizophrenia. METHODS: Our real world analysis is based on aggregated data from the Hungarian National Health Insurance Fund database. We selected adult patients (between 18-65 years) on quetiapine therapy with F20 schizoprenia ICD-10 code between January and March 2008. We compared the one-year discontinuation rate among once-daily vs twice daily quetiapine users. Discontinuation was defined as no prescribed antipsychotic medication in the N05A ATC group between May – July 2009. RESULTS: After 1 year 23.4% in the once-daily group compared to 27.2% in the twice-daily group discontinued the pharmaceutical therapy. Once-daily dosing reduced the relative risk of discontinuation by 13.9%. (χ2 test: p=0,017). The absoluate risk reduction was 3.8% (NNT=26.5). CONCLUSIONS: Our analysis indicates that once-daily dosing reduces the risk of drug discontinuation among schizophrenic patients. Short time-horizon, potential selection bias and confounding factors may limit the generalizability of our conclusions. Long-term observational study with multiple regression analysis based on anonimized individual patient records can confirm the validity of our findings.