The authors describe a clinical case of AIDS presented by three opportunistic infections (esophageal candidiasis, tuberculosis and atypical mycobacteriosis) and a dermatological manifestation--acanthosis nigricans--not described in medical literature as accompanying those entities. The exclusion of most common etiologies of acanthosis nigricans and its regression following treatment for those infections suggests that with AIDS it behaves like a paraneoplastic syndrome. Screening for HIV antibodies should be the rule whenever this dermatological manifestation is present.