OBJECTIVES: To compare treatment outcomes, by the Brief Psychiatric Rating Scale for Children (BPRS-C), and length of stay (LOS) for a group of child and adolescent psychiatric inpatients who were prescribed an atypical antipsychotic (AA) to those not prescribed an AA at discharge. METHODS: Data was collected from 48 facilities across the United States between July, 1999 and June, 2003. Descriptive statistics, ANOVA, and ANCOVA were used to compare differences between and within a group that was prescribed an AA (risperidone, olanzapine or quetiapine) (n = 1131) and a group that had not been prescribed AA at discharge (n = 1741). RESULTS: Inpatients were between 4-17 years old. Most patients were Caucasian, male, suffered from their disorders between 2-3 years, and lived at home with family prior to admission. At admission, the AA treatment group showed greater difficulty with respect to BPRS-C overall score (p <0.001); however at discharge, patients given AA showed greater improvement in BPRS-C subscores of behavior problems, thinking disturbances, and psychomotor excitation (p <0.03), but less improvement in the depression subscore than patients given no antipsychotic (p <0.02). Average daily dosage at discharge was 2.3 mg for risperidone, 156.3 mg for quetiapine, and 9.6 mg for olanzapine. After adjusting for covariates, AA patients had a longer LOS (26.4 v. 22.4 days) than patients given no antipsychotic (p = 0.017). AA patients treated with risperidone had significantly shorter LOS (17.3 days) than those treated with quetiapine (24.3 days) or olanzapine (28.1 days) (p = 0.024). CONCLUSIONS: Child and adolescent inpatients receiving AA had more significant emotional and behavioral disorders at admission than those not prescribed an AA. The AA treatment group showed greater improvement in behavior problems, thinking disturbances, and psychomotor excitation outcomes than patients given no antipsychotic, but less improvement in depressive symptoms. Among AA treated patients, LOS was significantly shorter for inpatients treated with risperidone.