A 38-year-old Caucasian woman with uncontrolled human immunodeficiency virus (HIV) infection was treated with highly active antiretroviral therapy (HAART) consisting of zidovudine, lamivudine, and nevirapine. Because her therapeutic response was inadequate, the HAART regimen was changed to abacavir, lamivudine, and lopinavir-ritonavir. Three months after this therapy was started, the patient developed progressive and notable hair loss. Her hair became fair and thin, and her appearance deteriorated considerably. Hair loss due to HAART was diagnosed. Lopinavir-ritonavir was stopped, and efavirenz was substituted; abacavir and lamivudine were continued. After 4 weeks, her hair growth substantially improved, as evidenced by rapid growth of new hair. Her general condition also improved. No relapse was observed with the new HAART regimen, and the patient's hair loss completely reversed in 8 weeks. Alopecia is a possible adverse event in HIV-infected patients treated with protease inhibitors, particularly indinavir. Our patient's severe and generalized alopecia was temporally related to the initiation and discontinuation of lopinavir-ritonavir. On the basis of the Naranjo adverse drug reaction probability scale, the adverse reaction was considered probable. Although generalized hair loss due to lopinavir-ritonavir is rare, clinicians should be aware of this potential adverse reaction of this widely used drug. If alopecia is severe or particularly distressing to the patient, the offending drug should be discontinued, and therapy with another HIV drug should be started.