3 cases of aplastic anaemia occurring in association with anti-tuberculosis chemotherapy are reported. The patients had been on anti-tuberculosis chemotherapy for 13, 11 and 14 months, respectively, prior to the diagnosis of aplastic anaemia. Agents used included streptomycin, thiacetazone, isoniazid, p-aminosalicylic acid and dimethylcarbazine. Recovery from aplasia did not occur 6, 1.5 and 0.8 months, respectively, after the discontinuation of the suspect myelotoxic agents and despite the use of myelostimulatory agents. All 3 patients died of haemorrhage secondary to thrombocytopenia. The observations are consistent with a protracted and probably irreversible damage of the bone marrow by anti-tuberculosis agent(s) in susceptible individuals.