A spectrum of enteropathies, characterized by small intestinal inflammation, reduced absorptive capacity, and increased intestinal permeability, commonly affect people in developing countries. This subclinical intestinal pathology facilitates microbial translocation across the compromised intestinal barrier, leading to chronic systemic inflammation that may adversely impact health. Environmental enteropathy (EE), ubiquitous among people living in unhygienic conditions, likely mediates two interlinked public health problems of childhood, stunting and anemia, and underlies poor oral vaccine efficacy in developing countries. Human immunodeficiency virus (HIV) enteropathy, which frequently overlaps with EE, may contribute to immune activation and modulate HIV disease progression. The interacting effects of infection and enteropathy drive a vicious cycle that can propagate severe acute malnutrition, which underlies almost half of under-5-y deaths. Enteropathies are therefore highly prevalent, interacting causes of morbidity and mortality in developing countries. Interventions to prevent or ameliorate enteropathies have potential to improve the health of millions of people in developing countries.