Three cases of purpura fulminans are reported. A five-year-old boy was successfully treated for purpura fulminans but had autoamputation of both legs and autolysis of bladder and urethra. He did not show any sign of shock at the onset of the disease. However, before an irreversible change of the skin lesion and organ involvement occurred, prompt diagnosis was effected, and aggressive treatment was given. An eight-day-old girl suffered from purpura fulminans at her four extremities, skull, bladder, ovary and vagina. Interesting findings were obtained in case 2, who had a positive family history. Several black spots in the extremities had disappeared spontaneously before admission, whereas the other lesions got progressively worse, with subsequent severe attack. Her general condition was not parallel to the severity of the disease. A 20-day-old boy had purpura fulminans after severe aspiration pneumonia, and showed a typical clinical course of the disease. In all patients, sudden drop of Hb and leukocytosis occurred after the skin lesion appeared. The diagnosis was unequivocal in these cases. Clotting time and FDP were good indicators of the progress of the disease in conjunction with the clinical features. Prompt diagnosis and aggressive therapy are necessary, not according to the patient's condition, but according to the laboratory findings and the serious nature of the disease. Internal haemorrhage must be considered as well as the skin lesion, this being a fatal complication.