Carcinoma of the parathyroid is an infrequent cause of primary hyperparathyroidism. Various authorities have estimated its incidence of 3 to 4% of all cases of primary hyperparathyroidism. Though several case reports on the parathyroid adenoma have been published in Korea, as far as our knowledge is concerned, no report on the parathyroid carcinoma can be found. In June, 1981, we experienced a case of parathyroid carcinoma in a 36 year old female with hyperparathyroidism. Clinical data and histopathological findings with light and electron microscope of the case were discussed and a brief review of the literature on this entity was made.