A taro strain (compatible or pathogenic), a pomegranate（Punica granatum) strain (compatible or pathogenic) and a sweet potato strain (incompatible or non-pathogenic) of Ceratocystis fimbriata Ellis et Halsted, were inoculated into taro (Colocasia esculenta Schott) tubers. Subsequently, the changes of the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in inoculated taro disks were observed. The results showed that the surfaces of the taro tuber inoculated by all the strains turned reddish under the same conditions after 10 h of inoculation. The taro strain and the pomegranate strain were pathogenic to and compatible with taro, while the sweet potato strain was non-pathogenic to and incompatible with taro. POD, SOD, CAT increased to a higher level in incompatible (sweet potato) strain than those in compatible (pomegranate and taro) strains after 25-30 h inoculation with those pathogens respectively. The surfaces of the taro tuber inoculated by all the strains turned mahogany after 10 h inoculation, whose MDA increased up to a peak at 20 h. 