A single injection of a long-acting oily preparation of chloramphenicol (Tifomycine) was compared with a five-day course of crystalline and procaine penicillin in the treatment of 131 adult patients with meningococcal meningitis. The clinical response to treatment was similar in the two groups of patients. Serial lumbar punctures showed a parallel fall in CSF cell count, protein and lactate and all posttreatment cultures were sterile. Single injection chloramphenicol treatment was cheaper and much easier to administer than penicillin. Long-acting chloramphenicol is thus an effective form of treatment for meningococcal meningitis and is likely to prove of particular value in the management of epidemics in areas with limited medical resources.