Abaecin is a proline-rich anti-bacterial peptide which is known to have high activity against Gram-negative bacteria and it is originally isolated from honeybee Apis mellifera. Since the anti-bacterial peptides including abaecin were identified in the hemolymph of A. mellifera infected with Gram-negative bacteria Escherichia coli, this result implies that honeybees express abaecin for defense against natural infection. Anti-microbial peptides including abaecin were also identified in the adult hemolymph of bumblebees. To investigate pharmacological and toxicological properties of abaecin from Bombus ussurensis, biological activities were evaluated by conducting anti-tumor, anti-microbial and cytotoxic activity assays. Abaecin exhibited significantly high anti-tumor activity against ovarian tumor cells SK-OV-3 and NIH; OVCAR-3 at 100 μM after 72 h treatment. Interestingly, abaecin showed none of anti-microbial activity against Gram-negative and Gram-positive bacteria. Since abaecin exhibited extremely low level of hemolytic activity against human erythrocytes, it may serve as a good model peptide for studying its potential as a selective anti-tumor drug.