Two adult, female rhesus monkeys (Macaca mulatta) became depressed, weak, anorectic, and adipsic. Auscultation of the thorax of 1 monkey revealed bilateral harsh rales. Neither monkey responded to therapeutic doses of antibiotics, and both died soon after treatment was started. Meningitis was demonstrated histologically and pure cultures of multiply antibiotic-resistant Klebsiella were isolated from the brains of both monkeys. Of 13 clinically normal rhesus monkeys in the same facility, 5 had multiply antibiotic-resistant Klebsiella spp in their pharynges.