Neurotropin was found to reduce brain oedema in an experimental model of brain infarction in the guinea-pig. A randomized double-blind controlled trial with Neurotropin was performed in 220 patients admitted within 24 h after an acute ischemic stroke. 35 of the neurotropin and 41 of the placebo-randomized patients had to be excluded. 10 included patients in the neurotropin and 13 in the placebo-treated group died within the study period of 15 days. A better clinical outcome was observed in the 65 included surviving neurotropin compared with the 56 placebo-treated patients. The size of the infarct and of the oedema zones was significantly more decreased on CT scans from Day 11 compared with Day 3 after stroke in the neurotropin than in the placebo treated group. Neurotropin is helpful in treating brain oedema, related to acute ischemic stroke.