Nephrogenic diabetes insipidus (NDI) occurred in a 43-year-old woman who had received lobenzarit disodium for the treatment of rheumatoid arthritis (RA). Her urine output was initially 3 //day and urine osmolarity was 203 mOsm//. Based on a sodium chloride loading test and a vasopressin loading test, she was diagnosed as having lobenzarit-induced NDI. Seven days after the cessation of the use of lobenzarit disodium, polydipsia and polyuria disappeared, and the vasopressin test showed a normal response. These findings suggest that lobenzarit induces a reversible form ofNDI as a side effect. The reports oflobenzarit-induced NDI in Japan during the past seven years are also reviewed.