A case of chondrosarcoma of the proximal Phalanx of the thumb is described. A review of the literature disclosed only sixteen documented cases of chondrosarcoma of the hand. There was no evidence that this tumor developed in an enchondroma. The concentration and distribution of radioactive sulphur in the tumor and in the other tissues of the digit were studied following injection of a tracer dose of S35-sodium sulphate. Such isotope studies are of value to distinguish benign from malignant cartilaginous tumors.