The pathology, etiology and epidemiology of anal cancer (CA) and the treatment and prognostic factors are reviewed. CA is a rare disease. However, the incidence is rising and is now 0.7 per 100,000 women and 0.4 per 100,000 men in Denmark. The median age is 60 years. Smoking and infection with human papillomavirus or HIV increases the risk of CA. The most important prognostic factors are tumour size, depth of invasion, inquinal lymph node involvement, differentiation and DNA ploidy. Previously CA was treated with abdominoperineal resection. Now sphincter preserving treatment with radiotherapy either alone or in combination with chemotherapy is preferred in most centers. Its is unsettled whether combined treatment is superior to radiotherapy only. Careful follow-up is warranted in order to perform salvage surgery in case of recurrent disease.