Idiopathic hypercalciuria may lead to bone loss via three pathogenic mechanisms described in HIV-negative patients: intestinal hyperabsorption, kidney loss and bone hyperabsorption. We conducted a cross-sectional study in a cohort of 217 HIV-positive antiretroviral-experienced patients, identifying hypercalciuria in 67 patients: the prevalence was 30.9% (95% confidence interval 27.4-37.0). The occurrence of hypercalciuria in subjects with normal values of parathormone may indicate an absorptive form of hypercalciuria. In this sample, other bone turnover markers and T-scores were not related to the condition. The results of this study show a high prevalence of idiopathic hypercalciuria in a group of antiretroviral-experienced patients. The consequences and the exact causes of this metabolic complication are not yet known and further investigation is needed.