Eleven healthy subjects volunteered to participate in a fiber supplement study and were instructed to consume oat husk tablets in addition to their regular diets. During a 2-week experimental period the subjects consumed 10 g oat husk per day. Blood samples were collected before breakfast between 8:00 and 9:00. As compared to baseline, 10 g oat husk supplementation per day resulted in a reduction of plasma plasminogen activator inhibitor type 1 (PAI-1) activity (p < 0.05). Except for an increase in glucose, no other statistically significant deviation from baseline was observed in measured blood parameters; tissue plasminogen activator activity, prourinary plasminogen activator, coagulation factor VII, total cholesterol, HDL cholesterol, LDL cholesterol, lipoprotein (a), triglyc-erides and insulin. A 6-week washout period returned the PAI-1 activity level to baseline.