Thiacetazone is used as a first-line antituberculosis drug in most of the developing countries of the South Pacific. Skine reactions are considered the major side effects of this drug. In Papua New Guinea, 2.5% of Melanesian patients who received thiacetazone for the treatment of tuberculosis developed skin reactions. The reaction appears to be caused by hypersensitivity rather than by toxicity and has distinct clinical features. The therapeutic regimen for tuberculosis in the developing countries of the South Pacific is not likely to change in the near future. Recognition of this potentially fatal complication of thiacetazone is important in the mamnagement of patients with tuberculosis in countries where the drug is used.