Fine-needle aspiration in hepatocellular carcinoma. Combined cytologic and histologic approach. Cytologic features of fine-needle aspiration (FNA) of hepatocellular carcinoma (HCC) have not been well documented. Most previous reports described only the the morphologic features of the tumor cells without considering the sinusoidal stroma. Cytohistologic correlation on tissue from the same aspirate has rarely been done. This report describes the cytologic patterns of 50 cases of HCC in terms of histologic pattern observed in cell blocks prepared from the same aspiration specimen and classified according to the World Health Organization (WHO) classification. Tumors were classified according to the predominant pattern. Thirty-two cases gave the trabecular pattern. Smears could be subdivided into a central-sinusoidal pattern (23 cases) and a peripheral-sinusoidal pattern (nine cases). One case gave the pseudoglandular pattern. Seventeen cases gave the compact pattern with inconspicuous sinusoids. In all cases sinusoids were easily recognized in cell block sections. Other cytologic features such as intranuclear cytoplasmic inclusions, eosinophilic globules, and bile secretion could be seen in both smears and cell blocks. Mallory's hyalin and ground glass inclusions were only recognized in cell blocks. More attention should be paid to the sinusoidal stroma for diagnosis of HCC in FNA; cell blocks should be more widely utilized to this effect; cytologic patterns could be classified according to the WHO histologic classification. 