OBJECTIVE: To compare subjective response and compliance of olanzapine-treated patients and patients treated with other antipsychotics in an observational prospective study (EFESO). METHODS: Outpatients entered the study when they received a new prescription of an antipsychotic drug. Patients treated with olanzapine (n=2128), risperidone (n=417) and haloperidol (n=112) were included in the analysis. Subjective response was measured using the 10-item version of the Drug Attitude Inventory (DAI-10). Treatment compliance was measured using a physician-rated 4 point categorical scale. Subjective response and compliance were compared between the treatment groups. Data were collected at baseline and after 3 and 6 months. RESULTS: Overall mean doses were respectively 13mg, 5.4mg and 13.6mg for olanzapine-, risperidone- and haloperidol-treated patients. All three groups had a positive subjective response to treatment. Olanzapine-treated patients had significantly higher DAI-10 score compared to both risperidone- and haloperidol-treated patients at 3 months (p=0.003 and p<0.001 respectively) and at 6 months (p<0.001 vs risperidone and haloperidol). Risperidone-treated patients had a higher DAI-10 score compared to haloperidol-treated patients at both 3 months and 6 months (p=0.003). Olanzapine-treated patients had significantly better treatment compliance compared to both risperidone- and haloperidol-treated patients at 6 months (p=0.001 and p=0.022 respectively). CONCLUSION: Despite the limitations of an observational study, these results suggest that in routine clinical practice, olanzapine-treated patients exhibit a superior subjective response and compliance compared to risperidone- and haloperidol-treated patients.