The distinction of hepatocellular carcinoma (HCC) from metastatic adenocarcinoma (MA) and cholangiocarcinoma (CC) in some cases requires the use of immunohistochemistry. CD10 has recently been suggested as a useful stain for HCC. We directly compared CD10 with other immunohistochemical markers, Hepatocyte, pCEA, and MOC31, that have previously shown to be useful for the distinction between tumors in the liver to help define the current panel of stains that most readily distinguishes HCC from CC and MA. One hundred previously well-characterized tumors in the liver were evaluated and included 25 HCC, 15 CC, and 60 MAs (15 each from breast, esophageal/gastric, pancreatic, and colorectal origin). Tumors were immunostained with the commercially available antibodies Hepatocyte, pCEA, MOC31, and CD10. CD10 stained 13 of 25 HCC and was rarely positive in MA and CC (3/75). Hepatocyte stained 24 of 25 HCC and was negative in all 75 MA and CC. pCEA stained 24 of 25 HCC and 71 of 75 MA and CC with the proper pattern of immunoreactivity, but the pattern of staining was difficult to interpret in several cases. MOC31 stained 1 of 25 HCC and 65 of 75 MA and CC. Hepatocyte was the most sensitive and specific single marker for HCC. CD10 is not a useful addition or substitution to the panel of Hepatocyte, MOC31, and pCEA. The combination of Hepatocyte, MOC31, and pCEA correctly classified 99 of 100 tumors in this study and is our proposed panel of immunostains for the initial workup of malignant tumors in the liver.