Urine-detecting alarms are prevalent in toilet training intervention research and clinical practice for individuals with intellectual and developmental disabilities, but the effects of urine alarms remain unclear. Urine alarms may function as punishing or reinforcing contingencies, or may merely alert trainers to accidents and improve treatment integrity. An alternating treatments design was used to compare the rate of accidents and the rate of in-toilet urinations during three conditions: intensive toilet training, intensive toilet training with an audible alarm, and intensive toilet training with an inaudible alarm. Participants were three young boys with autism. Results showed undifferentiated responding across conditions for all participants, with two of three participants appearing to acquire toileting skills during the comparison phase. We discuss the role of behavior irreversibility in light of our findings and associated study limitations. Future research should investigate inaudible urine alarms in settings with less adult support. Implications for professional practice given ethical guidelines for restrictive procedures are discussed.