In the past 18 months, the significant effect of highly active antiretroviral therapy and immune reconstitution on the incidence of opportunistic protozoan infections, mainly cryptosporidiosis and microsporidiosis, has been demonstrated in HIV-infected patients. The major therapeutic advances of the past 18 months concern microsporidiosis, for which the efficacies of fumagillin and albendazole have been assessed against Enterocytozoon bieneusi and Encephalitozoon infections, respectively. The efficacy of macrolides is still uncertain for the treatment of cryptosporidiosis; however, promising results were obtained with nitazoxanide. The incidence of toxoplasmosis has markedly decreased as a result of the efficacy of specific prophylaxis, and visceral leishmaniasis is still considered as an emerging opportunistic disease during AIDS. Curr Opin infect Dis 11:711-716. (C) 1998 Lippincott Williams & Wilkins.