To explore the optimal injection concentration and the changes of footpad skin histology and hematology of Asiatic toads (Bufo gargarizans) after injection of phytohemagglutinin-P (PHA-P), individuals were injected at footpad with PHA-P at three concentrations (1.0 g/L, 2.5 g/L and 5.0 g/L). The responsiveness to PHA-P in Asiatic toads exposed to different injection concentrations was tested and the optimal injection concentration was selected. Under the condition of the optimal PHA-P injection concentration, variations of different subtypes of leukocytes in the skin tissues of footpad position and circulation blood, as well as serum bactericidal capacity were measured when the PHA-P response reached the peak. All statistical analyses were performed using SPSS software packages (SPSS 17.0 for windows). One or two way ANOVA, or a repeated measurement one way ANOVA, or independent sample t test was used to compare the differences of body mass or percentage of different subtypes of leukocytes from skin tissues and circulation blood, or serum bactericidal capacity, or the responsiveness to PHA-P solutions among six time points. Results were presented as means ± standard error, and P < 0.05 was considered to be statistically significant. The results were as follows: PHA-P response did not display significant sex difference (P > 0.05, Fig. 2); The optimal PHA-P injection concentration was 2.5 g/L with the peak at 12 h after injection (Fig. 2). No significant group differences were observed for different subtypes of leukocytes from skin tissue with injected PHA-P or saline (or without any solution) at footpad positions (P > 0.05, Fig. 5); At peak time, percentage of lymphocytes was increased (P < 0.05, Fig. 7), but percentage of eosinophils was reduced (P < 0.05, Fig. 7) in circulation blood, and no significant difference was found for serum bactericidal capacity (Fig. 8). The optimal 2.5 g/L PHA-P concentration was appropriate for Asiatic toads. The peak of PHA-P response was not correlated with the dynamic changes of any subtype of leukocyte in the footpad skin tissues, but abundant lymphocytes might be activated, and the function of eosinophils might be attenuated in circulation blood, which may be regarded as the main factors causing Asiatic toads′ responsiveness to PHA-P solution.