Rhodococcus equi is an uncommon pathogen in humans that has occasionally been reported to cause infection in individuals with impaired cellular immunity. We summarize 30 previously published reports of human infection with R. equi and describe one additional case in a patient with AIDS. Eleven (35%) of the patients discussed in this report had AIDS or human immunodeficiency virus (HIV) infection, which is emerging as the leading cause of immunosuppression in cases of R. equi infection. Seventy-seven percent of all patients had pneumonia due to R. equi, and the infiltrate frequently cavitated. When HIV-infected patients were compared with those not infected with the virus, symptoms, age, and frequency of pneumonia were similar. Sputum and blood cultures were more likely to be positive in HIV-infected patients. Individuals with HIV infection also had a higher incidence of simultaneous secondary infections and higher mortality than non-HIV-infected patients (54.5% vs. 20%). The rate of survival for all patients was 75% when antibiotics were combined with surgical resection of infected tissue; in comparison, the survival rate among patients receiving antibiotics alone was 61.1%.