A case of haematogenous Serratia marcescens endophthalmitis in an HIV-infected intravenous drug addict is described. The patient was admitted with fever, ocular pain and visual loss in the right eye following an i.v. injection of pulverized buprenorphine. A vitreous humor culture grew S. marcescens. The patient was treated with i.v. ceftriaxone (2 g b. i. d.), i.v. amikacin (500 mg b. i. d.) and p. o. fosfomycin (1 g q. i. d.) for three weeks. The ocular infection was cured, although the visual function was lost, leading to blindness. To our knowledge, this is the second case in the reviewed Anglo Saxon literature of S. marcescens endophthalmitis in parenteral drug addicts.