In a previous study, we had shown that freeze-dried extracts of 12-year-old Armagnac could inhibit ADP-induced platelet aggregation in a dose- and duration-dependent manner, and reduce thrombus weight in an experimental rat arteriovenous shunt thrombosis model after 2-week oral treatment. Polyphenol content could however vary with age and origin of the brandy, and the onset and offset of the effect were not defined. To this end, we studied the effects of extracts of 5-, 10- and 15-year-old Armagnac from two different producers at 1, 5 and 25 mg/kg orally for 15 days, on the same rat arteriovenous shunt thrombosis model. We then studied the effects of 1, 3, 7 and 15 days of oral treatment with 5 mg/kg extracts of a 5-year-old Armagnac, and the effect 1, 3 and 7 days after a 1-week oral treatment of the same extract at the same dose. There was a dose-dependent decrease in thrombus weight, which was similar for both Armagnac origins for all ages. Extracts of 5- and 10-year-old Armagnac were similar, and more potent than extracts from 15-year-old Armagnac. There was a progressive decrease in thrombus weight over duration of treatment to 7 days, to about 50% of initial thrombus weight. The effect disappeared within 3 days after stopping a 7-day treatment. We confirm the dose-, age- and duration-dependent inhibition of arteriovenous shunt thrombosis in vivo by Armagnac extracts in rats.