This study evaluated the effect of switching to quetiapine vs. risperidone continuation on sexual functioning in outpatients with risperidone-associated sexual dysfunction. Outpatients (n=42, age>or=18 years) with schizophrenia or schizoaffective disorder who experienced risperidone-associated sexual dysfunction were randomized to 6 weeks of double-blind risperidone continuation (mean dose=4.1 mg/day, S.D.=1.2) or quetiapine switch (mean dose=290.0 mg/day, S.D.=55.2) treatment. The five-item Arizona Sexual Experience Scale (ASEX) assessed sexual functioning at baseline and subsequently at weeks 2, 4 and 6. A mixed-model analysis of repeated measures included gender and baseline ASEX and PANSS scores as covariates. There was no significant Treatment Group effect for ASEX total scores and ASEX sub-items, and no significant Treatment GroupxPeriod interaction for ASEX total scores and ASEX sub-items. Treatment Group effects were not significantly different in any of the prospective weeks for ASEX total scores and ASEX sub-items. Adjusted mean ASEX total scores were slightly lower in the quetiapine switch group than in the risperidone continuation group at weeks 2 and 6 (21.27 vs. 22.18 and 18.51 vs. 20.53, respectively), but were nearly identical at week 4 (20.01 vs. 20.15). In this pilot trial, sexual functioning did not differ significantly between outpatients receiving quetiapine switch vs. risperidone continuation, although the quetiapine switch group had slightly lower adjusted mean ASEX total scores at weeks 2 and 6.