Sweetpotato peels (SPP) are reported to be rich in phenolic compounds (Zhan, 1997), but are often disposed as waste or used as animal feed after processing. The objective of this study was to screen the phytochemical constituents, determine the antioxidant activity of the peels of 5 sweetpotato varieties and the use of sweetpotato peel extract in controlling rancidity in lard.