An AIDS patient with multiple opportunistic infections (Candida, Pneumocystis carinii and Isospora belli) was identified at the University Hospital, Kuala Lumpur. The patient presented with profuse diarrhoea associated with lethargy, anorexia and weight loss. Routine stool examination showed Isospora belli oocysts. The infection responded to treatment with trimethroprim-sulfamethoxazole but relapse occurred 8 weeks later. This represents the first documented case of isosporiasis to occur in an AIDS patient in Malaysia.