OBJECTIVES: i) to describe the long term evolution of HRQL of outpatients with schizophrenia ii) to analyse its association with antipsychotic use. METHODS: SOHO is an ongoing, 3-year, observational study of the treatment of schizophrenia in ten European countries. The primary objective of SOHO is to assess the costs and outcomes of treatment of schizophrenia using antipsychotics. Together with clinical measures, the EQ-5D (VAS score and tariffs) were administered at baseline, and 3, 6, 12, 18 and 24 months. The 'panel analysis' approach was used, since the outcomes were measured for the distinct post baseline epochs (0-6, 6-12, 12-18 and 18-24 months of treatment) Multivariate modelling was performed for each epoch, adjusting for baseline differences among patients. When using the second and subsequent episodes of patient treatment the baseline covariates were derived from the covariates collected when the patient switched treatment RESULTS: A total of 8,109 patients were included in this analysis (44% women; mean age:40); 24- month retention was 78.47%. Overall, the EQ-5D score after each period of continuous treatment was: Baseline; mean 0.6 SD 0.32: (0-6 months): 0.76 SD 0.26; (6-12 months ) :0.79 SD 0.24 (12-18 months): 0.81 SD 0.23; (18-24 months ): 0.82 SD 0.23 Olanzapine-treated patients had statistically higher EQ-5D utility improvements during the first 6 months compared with risperidone (difference in mean change:0.041; 95% CI: 0.023-0.06)-, quetiapine (0.032;0.006-0.059)-, oral (0.081;0.057-0.105)- and depot typicals (0.077;0.049-0.105)- treated patients. No statistical separation was observed between olanzapine, clozapine and amilsupride groups. These differences remaine during the 24-month follow-up CONCLUSIONS: Antipsychotic treatment is associated with sustained improvement in HRQL. The improvements in EQ-5D scores during the first 6 months for the Olanzapine group were significantly higher than the improvement for other antipsychotics and remaining thereafter, with the exception of Amilsupride and Clozapine where no significant separation was found.