Studies are reviewed of the inhibitory effect of flurbiprofen, given in doses ranging from 50 mg to 200 mg per day for 1 week, on platelet aggregation measured by biological tests (adenosine diphosphate and collagen methods). Flurbiprofen at doses of 50 mg and 100 mg daily had a peak time of action of between 1 and 2 hours, the effects usually disappearing after 24 hours, and 100 mg flurbiprofen caused a similar decrease in platelet aggregation to 1 g aspirin daily. In a clinical study of 72 patients with chronic glomerulonephritis treated with doses of flurbiprofen up to 200 daily there was a significant correlation between the parameters of aggregation measured and treatment, and between proteinuria and adenosine disphosphate aggregation when the flurbiprofen dose did not exceed 100 mg daily.