A rapidly enlarging left inguinal adenitis, with positive groove sign, and fever, chills, malaise, hypotension, headache, scarlatiniform rash, choleroid diarrhea, and proteinuria developed in an homosexual man who was positive for human immunodeficiency virus. The needle aspiration of the inguinal mass showed group A β-hemolytic streptococci and the blood cultures were negative, suggesting group A streptococcal cellulitis-adenitis with toxic strep syndrome. Treatment with penicillin and surgical drainage was successful. Bacterial infections associated with defective humoral immunity appear to be common in patients with acquired immunodeficiency syndrome (AIDS), and some of these infections have a remarkable extensive and lethal evolution. Therefore streptococcal adenitis should be considered in any patient with AIDS or AIDS-related syndrome in whom rapidly enlarging inguinal nodes develop.