Fifty cases of acinic cell carcinoma(ACC) of salivary glands were observed in a period of 22 years(l960-1982) in this hospital. 25 tumors out of the 50 occurred in the parotid gland, 7 in the submaxillary gland, and 18 in other minor salivary glands. Conventional microscopy revealed that ACC of salivary glands are composed of granulated acinic cells, clear cells, vacuolated cells, and intercalated duct cells. According to the different histological features, the authors suggest that ACC are to be classified into 6 types: cystic papillary, solid ethmoid, tra-beculopapillary, acinic adenoid, acinic nestlike and diffuse types. This classification facilitates the clinicians and pathologists to grasp the pathological cha- racteristies and diagnostic criteria and assessable prognosis and to accumulate the clinical material for research purposes.Thirty-seven patients out of the 50 have been followed up for years, the longest up to 19 years. 14 patients(37.8%)developed local recurrences. The five and ten year survival rates are 62.2% and 37.8% respectively.The differential diagnosis, histochemistry, histogenesis, and prognosis of ACC were discussed with a brief review of the literature concerned. Our data supports the assumption that ACC originates from the intercalated duct cells rather than from fully differentiated serous cells.