To explore the possibility of vaccine therapy for pancreatic cancer using ras oncogenic protein related antigen we studied whether cytotoxic T lymphocyte for tumor rejection can be induced by vaccination using the peptide relating mutated ras protein. Splenocytes from mice immunized by peptide (9-15 mer) relating mutated ras protein with normal splenocytes specifically increased in the culture with the peptide. The harvested splenic lymphocytes from the mice had peptide specific lysis against B 6 fibroblast incubated with the peptide. These results suggested that immunization using the peptide relating mutated ras peptide with autologous antigen presenting cell can be a vaccine therapy for pancreatic cancer.