BACKGROUND Incidence of Rhodococcus equi (R. equi) infection is increasing parallel to a greater prevalence of immunosupressed patients. This study aims to describe clinico-epidemiological characteristics of R. equi infections in a single hospital. METHODS Retrospective, observational study that includes any patient diagnosed of R. equi infection during the 1999-2007 period. Clinical and epidemiological characteristics were recorded. RESULTS Four patients were diagnosed of R. equi infection, with a mean age of 37.75+/-9.94 years old. All of them were male, infected with human immunodeficiency virus, and showed severe immunosuppression (mean CD4+ lymphocyte count of 83+/-55.2 cells/microl). Respiratory symptoms and cavitary pulmonary lesions were constantly present. R. equi was always cultured in blood and respiratory secretions. CONCLUSIONS R. equi infection is a rare disease that occurs predominantly in HIV infected patients, severely immunosuppressed patients and almost always causes cavitary pneumonia.