Calcium-dependent protein kinases are important decoders of calcium signals in plants, which are involved in plant immunity. We report isolation and functional characterization of a pathogen-responsive OsCPK20 gene in rice. The expression of OsCPK20 in rice was significantly induced following treatment with a Magnaporthe grisea elicitor. Transgenic rice plants containing constitutively active OsCPK20 exhibited enhanced resistance to blast fungus M. grisea. We also found thatOsCPK20 was significantly induced by drought stress, indicating that OsCPK20 might be involved in plant response to drought stress.