Houttuynia cordata Thunb. is used in folk medicine for diuresis and detoxiﬁca-tion. However, it has not yet been reported to have an anti-obesity effect. We found that the water extract of H. cordata leaves (WEH) inhibited the corn oil-induced increase in plasma triglyceride levels in mice. WEH also inhibited the oleic acid- and glycerol-induced increase in the levels of plasma nonesteriﬁed fatty acids and glycerol, respectively. Moreover, WEH had anti-obesity effects in mice with high-fat-diet-induced obesity. Therefore, WEH may be able to prevent or reduce obesity induced by a high-fat diet.