The authors evaluated serum CEA, TPA, CA19-9, SCC and CYFRA at diagnosis and in the follow-up of 18 anal canal tumors. Sensitivity at diagnosis was 38.8% for CEA, 55.5% for TPA, 16.6% for CA19-9, 50% for SCC and 5.5% for CYFRA. In the follow-up CEA showed 0% sensitivity and 73.3% specificity, TPA 33.3% sensitivity and 86.6% specificity, CA19-9 0% sensitivity and 80% specificity, SCC 0% sensitivity and 93.3% specificity, CYFRA 0% sensitivity and 100% specificity. The authors consider the usefulness of serum SCC and TPA at diagnosis of squamocellular anal cancer and of CEA in the diagnosis of cloacogenic tumors. Nevertheless these serum markers did not detect recurrences in the follow-up.