Changes in different biochemical parameters like total phenolic content, protein pattern, polyphenol oxidase, peroxidase and isozymes of peroxidase were compared in sterility mosaic resistant (Hy3C) and susceptible (Type-21) pigeonpea varieties at different growth stages both under inoculated and uninoculated conditions. Resistant variety was characterized by the presence of specific isoperoxidase and proteins but only little difference was recorded between resistant and susceptible variety with respect to preformed or induced total phenolics and peroxidase activity. The activity of polyphenol oxidase increased substantially in susceptible variety following infection. Role of these changes is discussed in relation to disease resistance.