OBJECTIVE: Percutaneous ethanol injection therapy (PEIT) and percutaneous microwave coagulation therapy (PMCT) are effective treatments for small hepatocellular carcinoma (HCC). There are no clear standards, however, for the selection of PEIT or PMCT. We determined standards based on local recurrence. METHODS: The subjects were 88 patients with solitary HCC measuring less than or equal to 30 mm in diameter, who were Created by PEIT (n = 45) or PMCT (n = 43) and judged to be cured using computerized tomography (CT) with contrast medium after treatment. Patient characteristics, including age, gender, viral markers, Child-Pugh classification, tumor size, tumor cell differentiation, and serum alpha-fetopretein (AFP) concentration we analyzed, and the factors influencing the local recurrence in the PEIT and PMCT groups were determined, using univariate and multivariate analysis. RESULTS: Univariate analysis indicated that tumor-cell differentiation and serum AFP concentration influenced local recurrence in the PEIT group, and tumor size did so in the PMCT group. Multivariate analysis revealed that tumor cell differentiation influenced local recurrence in the PEIT group, and tumor size did so in the PMCT group. PEIT was effective for treating well-differentiated HCC, and PMCT was effective for treating HCC measuring less than or equal to 15 mm in diameter. PMCT was superior to PEIT for treating patients with HCC measuring less than or equal to 15 mm in diameter. In such cases with well-differentiated HCC, PEIT was as effective as PMCT. CONCLUSIONS: The selection of PEIT or PMCT to treat patients with WCC should be based on tumor size and cell differentiation. (Am J Gastroenterol 1999;94:1914-1917. (C) 1999 by Am. Coll. of Gastroenterology).