The present study aimed to investigate the effects of Hsian-tsao (Mesona procumbens Hemsl.) and its active compound on blood pressure, lipid peroxidation and total antioxidant status of spontaneously hypertensive rats (SHRs). Male SHRs were orally administrated either a water extract of Hsian-tsao (WEHT) (1.0 g/kg) or caffeic acid (CA) [0.1 g/kg of body weight (BW)] on a daily basis for 6 weeks. The results indicated that both hepatic and plasmatic malondialdehyde concentration were increased and total liver glutathione (GSH) levels and antioxidant enzyme activities were decreased in SHRs when compared to the control Wistar Kyoto rats at the end of the trail. In SHRs, oral administration of WEHT or CA for 6 weeks reduced blood pressure as well as plasma and hepatic malondialdehyde levels and increased hepatic antioxidant enzyme activities when compared to SHRs control rats. Reverse transcriptase-polymerase chain reaction results indicated that the changes in hepatic antioxidant enzyme mRNA levels by WEHT or CA were similar to those noted in the enzyme activity levels. The hepatic levels obtained from WEHT or CA-administrated rats had significantly greater oxygen radical absorbance capacity values and total GSH levels than those of control rats. Following oral administration of CA, phenolic acid was detected in the plasma, and Cmax value after 1.0 h administration was 0.92 μmol/L. These findings indicate that a supplement of Hsian-tsao may prevent development of increased blood pressure and enhance the total antioxidant status in vivo.