The global spread of HIV infection over the past 25 years presents new challenges to physicians. HIV produces multi-system disease and can present to primary care physicians or to any hospital specialist department. In the twenty-first century, HIV has joined syphilis in the differential diagnoses for many illnesses. This article is aimed at the general physician and describes the common features of HIV infection. The key points to note are: epidemiology; clinical features of opportunistic infections, tumours, and neurological disease; when to test for HIV; benefits of treatment; and complications of treatment. Throughout this article I have avoided the expression ‘AIDS’ because it means different things to different people. The North American definition is based on laboratory evidence of immunodeficiency but the European definition is based on historical clinical features which are often independent of immunodeficiency. I prefer to speak of HIV and its spectrum of clinical disease.
