This randomized study compared the fibrinolytic circadian rhythm of healthy older men and older women (average age 66 ± 5), before and after 6 months of endurance training versus stretching controls. Compared with men, women at baseline had similar rhythms for tissue plasminogen activator (t-PA) activity and plasminogen activator inhibitor 1 (PAI-1) activity, but lower levels of total t-PA antigen. In men (N = 16), endurance training increased ˙VO2max 15% (P < 0.001), while decreasing PAI-1 activity 37% (P = 0.034) and total t-PA antigen 18%(P = 0.0003) between midnight and 6 a.m., but did not affect t-PA activity. In women (N = 9), endurance training increased˙VO2max 18% (P = 0.003), and increased t-PA activity 20%(P = 0.027) and total t-PA antigen 55% (P = 0.007) between 10 p.m. and 4 a.m., but had no effect on PAI-1 activity. After endurance training there were no significant differences in the fibrinolytic circadian rhythm of men versus women. Six months of nonaerobic stretching had no effect on ˙VO2max or fibrinolysis in men (N = 11) or women(N = 8). This study indicates that potentially favorable changes occur in fibrinolytic factors after endurance training in older men and older women.