Objective: To investigate the short-term effects of HMR 3339, a novel selective estrogen receptor modulator, on markers of coagulation and fibrinolysis. Study design: In a multicenter, 14-week, randomized, placebo-controlled, double-blind, dose-ranging study, healthy postmenopausal women received daily placebo (n = 22), HMR 3339 2.5 mg (n = 25), HMR 3339 10 mg (n = 24), HMR 3339 50 mg (n = 24), or raloxifene 60 mg (n = 23). Statistical analysis was performed using standard parametric tests. Results: After 12 weeks, compared with placebo, HMR 3339 50 mg induced the largest mean percentage changes in antithrombin (-14.6%, P < .001), protein C (-12.9%, P = .029), and fibrinogen (-26.3%, P = .001). Decreases were observed in the HMR 3339 2.5 mg group, compared with placebo, in tissue-type plasminogen activator (-55.0%, P = .026 after 4 weeks), plasmin-α2-antiplasmin complex (-85%, P = .031 and -63.3%, P = .008, respectively, after 4 and 12 weeks), and D-dimer (-91.4%, P = .018 after 12 weeks). Compared with placebo, raloxifene 60 mg decreased total protein S (-8.2%, P = .009) after 4 weeks and antithrombin (-6.0%, P = .034) and fibrinogen (-18.1%, P = .007) after 12 weeks. Conclusion: HMR 3339 and raloxifene decreased fibrinogen levels. In the low dosage, HMR 3339 showed potentially beneficial effects on some markers of fibrinolysis. Both drugs impaired the anticoagulatory potential. © 2005 Mosby, Inc. All rights resrved. Chemicals / CAS: antithrombin, 9000-94-6; fibrinogen, 9001-32-5; protein C, 60202-16-6; raloxifene, 82640-04-8, 84449-90-1; tissue plasminogen activator, 105913-11-9; Biological Markers; Estradiol, 50-28-2; HMR 3339; Raloxifene, 84449-90-1; Selective Estrogen Receptor Modulators