Leukocytes are reportedly the first line of the innate immune defense and essential for thecontrol of common bacterial infections. Therefore, in this work, the antibacterial activity ofcrocodile leukocyte extract against  Propionibacterium acnes was evaluated, and we alsocharacterized the related activity of skin infection. The leukocyte extract showed the minimuminhibitory concentration to be 100 μ g/ml to  P. acnes . SEM imaging demonstrated that theleukocyte extract adversely affected  P. acnes cell permeability in a concentration-dependentmanner.  Furthermore,  the  crocodile  leukocyte  extract  could  significantly  reduceproinflammatory markers and decrease inflammatory signs in infected mouse ears. The crudeleukocyte extract was further purified using FPLC and RP-HPLC. The resulting fraction F5was indicated as the anti-acne peptide-containing fraction. The molecular mass of the peptidecontained in F5 was calculated to be 4,790.5 Da. N-Terminal sequencing revealed the aminoacid sequence as GPEPVPAIYQ, which displays similarities to immunoglobulin A andleucine-rich repeat neuronal protein. This is the first reported amino acid sequence of acrocodile leukocyte extract that possesses anti-acne activity. To attempt to use it in a prototypecosmetic, an anti-acne gel containing crude crocodile leukocyte extract was formulated,resulting in seven gel formulations (G1, G2, G3, G4, G5, G6, and G7). The formulations G5, G6,and G7 exhibited 2-fold higher anti-acne activity than G1 - G4. Investigation of acceleratingstability studies of anti-acne gel formulations G5, G6, and G7 demonstrated that a low storagetemperature (4ºC) is suitable for maintaining the physical properties and biological activity ofthe anti-acne gel products.