Moriyama Y et al. - This is a case report of a 51-year-old HIV-positive man treated with atazanavir for 9 months presented with anuria following right flank pain. A yellowish stone composed of pure atazanavir was found at the right ureteral orifice, and retrograde pyelography revealed a filling defect in the left ureter found to be caused by an atazanavir stone. The patient’s renal function recovered after removal of these stones.