Representatives of three species of strawberries (Fragaria virginiana, F chiloensis and F x ananassa) were evaluated for antioxidant capacity, scavenging capacity for reactive oxygen species (ROO, -OH , (1)0(2) and O(2)), and inhibitory effect on proliferation of A549 human lung epithelial cancer cells. Differences among the strawberry genotypes were observed for all three qualities. High antioxidant and scavenging capacities were found in 'CFRA 0982', 'JP 95-1-1', NC 95-19-1 and RH 30. Lowest antioxidant and scavenging capacities were found in 'AlIstar'. There was also a relationship between scavenging capacity and the inhibition of cancer cell proliferation. The correlations (R2) between the scavenging capacities for the reactive oxygen species and the inhibition of cancer cell proliferation were 0.8074, 0.8279, 0.7862 and 0.7761 for ROO, -OH, (1)0(2) and O(2), respectively. These results suggest that antioxidants, specifically their scavenging capacities, may play an important role in the antiproliferative activity of strawberries. This study also identified strawberry germplasm of value in developing cultivars useful for cancer prevention.