Two cases of adult respiratory distress syndrome were treated in a series of 26 patients suffering from colchicine overdose. The syndrome appeared between the 24th and 72nd hours. It was characterized by the presence of interstitial as well as alveolar oedema seen on chest roentgenograms. Haemodynamic investigation showed a hyperkinetic state with moderate precapillary pulmonary arterial hypertension. In addition, multivisceral phenomena were observed in all cases. Post-mortem examination revealed interstitial and alveolar pulmonary oedema with haemorrhagic or macrophagic alveolitis often accompanied by hyaline membrane. The physiopathology of ARDS occurring in colchicine poisoning appeared to involve such different factors as infection, the presence of a state of shock and disseminated intravascular coagulopathy. The direct toxic action of colchicine on pneumocyte microtubules and the inhibition of surfactant production were a probable cause. The responsibility of colchicine in leukocyte aggregation remains to be determined.