To examine the relationship between perceived locus of control over treatmen and psychological adjustment to end-stage renal disease (ESRD), 138 individuals were assessed for beliefs about control over health outcomes with the Multidimensional Health Locus of Control Scales, and for psychological adjustment using the Affect Balance Scale and the Index of Weil-Being. Results indicated that locus of control for health was not related to treatment modality, but was significantly related to indicators of emotional adjustment. Data suggest that perceived locus of control over treatment outcome acts as a moderator variable in predicting psychological adjustment to ESRD. One year later, 47 of the original subjects participated in a follow-up study. The relationship between perceived locus of control and psychological adjustment was replicated. Implications for the relationship between locus of control over health and psychological and physiological well-being following renal failure are discussed.