During a seven-year period, symptomatic cytomegalovirus (CMV)-infection was diagnosed in 21.5% (n = 10) of all AIDS patients at the National Hospital of Norway (retinitis n = 8, colitis n = 3, pneumonitis n = 2, gastritis n = 1). Symptomatic cytomegalovirus-infection was associated with a poor long-term prognosis (median survival 174 days, range 10-415). Median CD4+ lymphocyte counts at onset of symptomatic cytomegalovirus-infection was 24 x 10(6)/l (range 6-68). Regular ophthalmological examination of HIV-infected patients with severe immunodeficiency, and endoscopy with multiple mucosal biopsies in patients with suspected cytomegalovirus-infection of the gastrointestinal tract, were of major importance in diagnosing symptomatic cytomegalovirus-infection. Six patients received an induction course of ganciclovir, and foscarnet was administered in two patients due to leukopenia. Problems of toxicity to the available anti-CMV agents make the development of additional therapeutic approaches desirable.