Lactobacillemia, an uncommon cause of bacteremia, has been reported to occur in one renal transplantation patient who was also infected with human immunodeficiency virus (HIV). We present the cases of three patients with AIDS in whom lactobacillemia developed. All three patients had late-stage AIDS with CD4 cell counts of < 55/mm3, all had indwelling central venous catheters, and all were recently or concomitantly blood culture-positive for coagulase-negative staphylococci. In addition, two of the three patients had recently received vancomycin therapy. These three cases provide the first association of lactobacillus bacteremia and AIDS.