Salicylic acid (SA) is an important signaling hormone in plants, playing a role in induced defense responses. After treatment with exogenous SA, changes in liposygenase (LOX) activity, phenylalanine ammonialyase (PAL) activity and peroxidase (POD) activity increased significantly compared with those in contro1. The activity of three enzymes increased more remarkably and rapidly on the leaves of the incompatible rice line than those in the compatible rice line. CAT activity decreased on the leaves of two rice cultivars. Pathogenesis-related proteins (PR proteins) are a characteristic of systemic acquired resistance (SAR) in plants. The results showed that changes in two PR proteins, chitinase and β-1,3-glucanase, were also increased more remarkably and rapidly on the leaves of the incompatible rice line than on those of the compatible rice line. The results also showed that endogenous SA had little change either on the leaves of the two rice cultivars after inoculation with exogenous SA. The results suggest that defense-related enzymes and SAR in rice leaves induced by exogenous SA might play an important role in rice resistance to rice blast.