From 1986 to 1995, we retrospectively reviewed the records of 40 of 125 patients (32.0%) with acquired immunodeficiency syndrome (AIDS) who presented with extrainguinal lymphadenopathy. Most of the patients had an advanced stage of HIV infection with a mean CD4 lymphocyte count of 44/mm3. AIDS-defining opportunistic infections and malignancies were present in most patients and the neck region was the most common site of involvement. The etiology of lymphadenopathy was established in 26 patients. Tuberculous lymphadenitis was the most common cause, followed by lymphadenopathic Kaposi's sarcoma, benign reactive hyperplasia, cryptococcal lymphadenitis and disseminated Mycobacterium avium complex infection. Characteristic histopathologic findings were detected in 19 patients and 7 had presumptive tuberculous infections. The remaining 14 patients had no definitive etiology for their lymphadenopathy. As the causes are variable and the number of HIV/AIDS cases is increasing in Taiwan, more patients with lymphadenopathy, especially in the early stages of HIV infection will be encountered. Therefore, it is essential that diagnostic histopathologic and microbiologic studies be performed for appropriate and timely treatment.