Kalopanax pictus is a deciduous tree used in traditional medicine. The leaves have been consumed as a vegetable in Korea. In this study, we examined the antioxidant and anti-inflammatory capacity of the extracts from K. pictus leaves in vitro using hydroxyl radical scavenging assay, DNA nicking assay, metal chelating assay, reducing power assay, DPPH free radical scavenging assay, and nitric oxide inhibition assay. The effect of the hot water extract was stronger than that of the methanolic and ethanolic extracts in all of the assays. Moreover, the total phenolic contents in the extracts were measured by spectrophotometry. Meanwhile, a regression analysis revealed a correlation coefficient between the content of phenolics and antioxidant activity. Overall, our data suggest that K. pictus leaves possess significant antioxidant properties.