NK-2 synthetic peptide derived from cationic core region of porcine NK-lysin has an antimicrobial and antitumor polypeptide that is considered to play a pivotal role in innate defense immunity. To evaluate the antimicrobial properties of synthetic chicken NK-lysin peptides, we investigated cytolytic activity against apicomplexan parasites like Eimeria sporozoites, Neospora tachyzoites and Cryptosporidum sporozoites. The chicken NK-2 (cNK-2) lytic peptide which corresponds to amino acid residues of porcine NK-2 peptide significantly disrupted Eimeria and Cryptosporidum sporozoites and Neospora tachyzoites. In contrast, no bactericidal activity was observed on E. coli BMH71-18. The cNK-2 lytic peptide is novel antimicrobial agent which can be used to intervene and treat economically costly infections in the animal industry.