A nephrotic syndrome has been observed rarely in association with thymoma. In most of the reported cases, it occurs when the thymoma is in remission; histological examination generally shows minimal change disease. We report a case of a 43-year-old man presenting with minimal lesion nephrotic syndrome at the time of the diagnosis of thymoma and myasthenia gravis, which persists despite remission of the thymoma. The role of a disorder of T-cell function and of circulating cytokines is discussed.