Over the past 2 decades, numerous changes have occurred in the demographics and clinical course of the human immunodeficiency virus (HIV) infection. Since the initial reports of mucosal candidiasis, severe weight loss, and Pneumocystis carinii pneumonia as presenting manifestations of the late stages of immunodeficiency, clinicians have recognized a wide spectrum of manifestations associated with HIV disease. The original reports of severe immunodeficiency were simply the "tip of the iceberg." Advances in antiretroviral therapy and prevention of opportunistic infections have made early diagnosis important. Recognition of cases in earlier stages facilitates opportunities to prevent transmission throughout the population, especially in high-risk groups and pregnant women. Recent evidence suggests that antiviral therapy for primary HIV infection may beneficially alter the course and long-term outcome in persons infected with HIV. This article reviews common presenting syndromes of HIV to aid clinicians in establishing an earlier diagnosis.