Forty-nine episodes of bacteremia and fungemia occurred in 38 of 336 patients with the acquired immunodeficiency syndrome seen at our institution since 1980. There were five types of infections. Infections commonly associated with a T-cell immunodeficiency disorder comprised 16 episodes and included those with Salmonella species, Listeria monocytogenes, Cryptococcus neoformans, and Histoplasma capsulatum. Infections commonly associated with a B-cell immunodeficiency disorder included those with Streptoococcus pneumoniae and Haemophilus influenzae. Infections occurring with neutropenia were caused by Pseudomonas aeruginosa, Staphylococcus epidermidis, and Streptococcus faecalis. Other infections occurring in the hospital were caused by Candida albicans, Staphylococcus epidermidis, enteric gram-negative rods, Staphylococcus aureus, and mixed S. aureus and group G streptococcus. Other infections occurring out of the hospital included those with S. aureus, Clostridium perfringens, Shigella sonnei, Pseudomonas aeruginosa, and group B streptococcus. Because two thirds of the septicemias were caused by organisms other than T-cell opportunists, these pathogens should be anticipated during diagnostic evaluation when formulating empiric therapy.