Rhodococcus equi is an aerobic, gram-positive, non-motile pleomorphic bacillus infecting immunocompromised patients. Forty-nine cases of Rhodococcus equi infection have been reported, mainly in patients infected with the human immunodeficiency virus (HIV). A case in which Rhodococcus equi caused severe pulmonary infection, the most common presentation, is described. Clinically, patients have symptoms of pneumonia with hemoptysis as a prominent feature. X-ray will often show a cavitating upper-lobe infiltrate, resembling infection with mycobacteria. Rhodococcus equi is easily cultured from blood or sputum on standard media, but is frequently regarded as a contaminant. Mortality from Rhodococcus equi pneumonia is high (25%) and early surgical intervention has been recommended. Based on this review, the benefit of surgery seems dubious, whereas good results have been obtained using long-term antibiotic treatment with erythromycin plus rifampicin, or vancomycin in combination with either of these antibiotics.