Anal canal carcinoma is a rare clinical entity accounting for 1 to 3 per cent of all gastrointestinal malignancies. Abdominoperineal resection used to be the primary modality of treatment. However, recurrence rates of 20 to 40 per cent were observed after this mutilating procedure. In recent years, multimodality therapy with radiation and chemotherapy has shown at least equal results with the intention to preserve sphincter function. The objective of this study is to describe our experience at Harbor-UCLA Medical Center during the past 4 decades (1955-95), emphasizing changes in demographics, clinical presentation, and impact of multimodality therapy. Seventy-eight patients with the diagnosis of anal canal carcinoma were included. A steady increase in the incidence of anal carcinoma in younger people was observed (24% less than 64 years old for the 1955-65 period versus 75% for 1986-95 period). A female predominance was found in 1955-65 period, with F:M ratio 1.5, and a majority of male cases was seen in the last period (1986-95). Abdominoperineal resection was the preferred treatment during 1955-65, whereas during 1986-95 chemoradiation was the treatment of choice. We observed a trend from primary surgical treatment toward chemoradiotherapy with improvement in survival and preservation of ano-rectal function. Since 1988, we have not performed an abdominoperineal resection for primary treatment of anal carcinoma. Survival analysis was made grouping the patient population according to primary treatment. Higher survival rates were observed in the groups that received chemoradiotherapy (P = 0.0368) either as adjuvant or primary therapy. Chemoradiotherapy should be recommended as primary therapy to most patients.