C57BL/6 mice sensitized intraperitoneally with the anti-idiotypic monoclonal antibody-NP30 of Schistosoma japonicum and then injected with vital egg suspension directly into spleen were used as the experimental models of hepatic egg granulomas in this study. The soluble egg antigen(SEA) sensitized group was used as positive control and the SP2/0 ascites injected group as negative control. The results showed that the size and volume of hepatic egg granulomas in the NP30 sensitized group increased obviously 4 days after egg injection and that a large number of eosinophiles appeared in egg granulomas. The size and volume of egg granulomas reached the peak values at d8 and d15 after egg injection, respectively. The peak values of the NP30 sensitized group were similar to those of the SEA sensitized group (P > 0.05). The size and volume of egg granulomas in the SP2/0 ascites injected group did not reach the peak values, which were less than those of the group sensitized with NP30 (size: P < 0.05; volume: P < 0.01), until d32 after egg injection. Our study suggests that NP30 may play a sensitizing role in the formation of hepatic egg granulomas.