Free radical scavenging activities (FRSA) of the crude aqueous extracts from Rosa rugosa fresh flowers at different developmental stages on l, l-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl free radicals, and their polyphenolic concentration, were investigated. FRSA ranged from 73.5% to 40.2% for DPPH, from 32.2% to 14.3% for hydroxyl, and from 84.6% to 78.0% for superoxide. The polyphenolic concentration varied from 19.8 to 6.9 mg catechin equivalents (CE)/g fresh weight (FW). There was a reduction in FRSA for DPPH and hydroxyl, as well as polyphenolic concentration. The decrease in polyphenolic concentration was positively correlated with declines in free radical scavenging of DPPH (r 2 = 0.961, P < 0.01) and hydroxyl free radicals (r 2 = 0.993, P < 0.01). These results demonstrated a close link between rose development, polyphenolic concentration, and antioxidant activity with stage 1 exhibiting the best polyphenolic concentration and free radical scavenging potential.