Tenosynovial chondromatosis has not been well recognized because of its rarity, but it is clinically important because of its high rate of recurrence. We report here a case of tenosynovial chondromatosis with deposits of crystalline material that appeared to be sodium urate (gouty tophi). A 37-year-old Japanese man was admitted because of a hard mass in his left third finger. He had undergone surgery at the same anatomical site four and seven years previously. The roentgenogram revealed a soft tissue mass in the flexor aspect of the proximal phalanx. At operation, the tumor was found to have arisen in the tendon sheath. Histopathological examination showed that the tumor was composed of well-defined, multiple, cartilaginous nodules that were surrounded by tenosynovial tissue. A few of the nodules were calcified. The chondrocytes had mild atypia, and were immunopositive for S-100 protein. A diagnosis of tenosynovial chondromatosis was made. The nodules also contained crystalline deposits, which bore a histological resemblance to gouty tophi. We were unable to define the exact nature of these deposits even by transmission electron microscopy and electron roentgenographic microanalysis. Crystalline deposits in chondromas of soft tissue have been reported but not in tenosynovial chondromatosis.