A familial occurrence of acute paraquat (PQ) poisoning is reported. The mother administered a PQ solution to their 3 children aged 8 y, 6 y and 15 mo and then ingested an unknown amount of the herbicide herself. In the absence of history or diagnostic signs, the poisoning was initially misdiagnosed as gastroenteritis. Thirty h after the ingestions, serum PQ concentrations of the children were 60, <6 and 25 ng/ml respectively. Hemoperfusion was performed on all patients, and 2 of the children also received plasmapheresis and erythropheresis. The 3 children recovered fully but the mother died. According to these patients' data, the extracorporeal techniques had little effect on PQ removal, and the decreases in serum PQ were related to its urinary excretion.