Abstract: Objective To explore the effects of Herba Scutellariae Barbatae flavonoids (HF) in delaying aging of Caenorhabditis elegans and human umbilical vein endothelial cells (HUVECs) in vitro. Methods The effects of 30 or 50 mg/L of HF on nematode life span, reproductive capacity, oxidative stress, and antioxidant enzyme activity of C. elegans were assessed, and the effects of HF on the expressions of the genes encoding antioxidant enzymes and the aging-related genes were analyzed using real-time RT-PCR in both C. elegans and cultured HUVECs. Results Compared with the blank control group, C. elegans with HF treatment showed significantly improved mean and maximum lifespan with a prolonged mean lifespan under acute heat stress at 35 ℃. HF treatment did not impair the reproductive capacity or cause significant changes in the offspring number of C. elegans. In addition, HF enhanced SOD and CAT activity and up-regulated the expression of daf-16 and sir-2.1 (SIRT1) genes in C. elegans and HUVECs. Conclusions HF may delay aging of C. elegans and enhance their resistance to acute heat stress without damaging their reproductive capacity possibly by up-regulating the activity of antioxidant enzymes and expressions of antioxidant genes. HF also may protect endothelial cells against oxidative damage.