Antitumor activity of Lactobacillus casei YIP 9018(LC9018) was studied in mice by using sarcoma 180(S-180) and Lewis lung carcinoma (3LL). Following the eatablishment of in vivo tumor models such as ascites form S-180, solid form S-180 and 3LL for estimating antitumor activity of Lactobacilli, optimal dose and injection route of heat-killed LC9018 for supperssion of local tumor were examined. Administration of 100ng/mouse of LC9018 significantly inhibited the growth of ascites form S-180, solid form S-180 and 3LL.