The morbidity, mortality, and social disruption caused by the human immunodeficiency virus (HIV) pandemic continue to weigh disproportionately on resource-poor regions of the tropics. As a result, the potential for significant epidemiological, biological, and clinical interactions between HIV and other tropical pathogens is great. An overview of the available data on tropical helminths, fungi, bacteria, and viruses is provided here; interactions between HIV and tropical protozoa are covered in a related mini-review in this issue of Clinical Infectious Diseases. Special attention is given to evidence relevant to the hypothesis that helminth coinfection plays a particularly important role in accelerating the pace of HIV pathogenesis in the tropics.