The response of 50 patients who underwent hepatectomy for hepatocellular carcinoma measuring 3 cm or less (at the time of surgery) to transcatheter oily chemoembolization was evaluated. The response was assessed in 5 categories, A: complete necrosis (100%), B: necrosis of at least 95%, C: at least 80%, but less than 95%, D: at least 50% but less than 80%, and E: less than 50% of the tumor cells. Response A was observed in 19 patients (38%), B in 7 (14%), C in 9 (18%), D in 7 (14%), and E in 8 (16%). These results were classified with respect to the histological degree of tumor differentiation, the WHO histological classification, the microscopic patterns of tumor growth, and macroscopic classification. The response was evaluated in relation to the histological grade of tumor differentiation and the WHO histological classification in all categories of response except response A, and there was no significant difference between the categories. The response was obviously better with the expansive type than with the replacing type. Single nodular type lesions were more responsive than the single nodular type lesions with extranodular growth and the contiguous multinodular type. Pretreatment estimation of the microscopic patterns of tumor growth and macroscopic classification appears to be valuable in predicting prognosis.