A case of a HIV-positive patient hospitalized with acute abdomen secondary to infection by cytomegalovirus (CMV), is presented. Infection by CMV is frequent in HIV-positive patients, with a relevant intestinal affection. However, its presentation as acute abdomen is more rare, although it has to be considered given that the demonstration of the presence of CMV and its potential pathogenic power have important therapeutic connotations. Currently, the use of diagnostic techniques based in specific monoclonal antibodies and DNA hybridization methods increases the diagnostic sensitivity of the traditional methods based on histological demonstration of the cytopathic effect and/or viral cultives.