This subgroup analysis of symptomatically stable patients with schizophrenia or other psychotic disorders in the StoRMi trial determined the efficacy and tolerability of risperidone long-acting injectable in patients changed from oral risperidone monotherapy. Risperidone long-acting injectable was administered open-label (dosage 25/37.5/50 mg every 2 weeks for 6 months). In total, 568 patients (60% men, mean age 36-40 years) were included and grouped according to pre-trial oral risperidone dosage (56% < or =4 mg; 30% >4 to < or =6 mg; 14% >6 mg). Most patients (71-85% across groups) were diagnosed with schizophrenia. At endpoint, risperidone long-acting injectable dosages partly correlated with the previous oral risperidone dosage. Some patients previously on high dosages of oral risperidone responded well to lower risperidone long-acting injectable dosages. Efficacy significantly improved from baseline to endpoint in all groups; total Positive and Negative Syndrome Scale score improved by > or =20% in 39% of all patients. Clinical global impression symptoms, global assessment of function scores, and the SF-36 mental component summary score significantly improved in all groups. Hospitalizations were reduced by 74-80%. Extrapyramidal symptom rating scale scores were significantly better at endpoint (P< or =0.001). These results indicate that further improvement in symptom control can be seen after a change to risperidone long-acting injectable in clinically stable patients previously treated with oral risperidone.