Blood-brain barrier (BBB) is the major obstacle for drug delivery into the central nervous system (CNS).  However, there is no ideal model animal for the study of BBB permeability till now.  Currently zebrafish (Danio rerio) has emerged as a powerful model organism for the study of vertebrate biology.  In this study, the feasibility of using zebrafish as model animal was investigated for BBB permeability by comparing the results of administration of BBB-penetrating peptide and protein to mouse and zebrafish.  The results showed that the BBBs of mouse and zebrafish were similar in molecular permeability.  Additionally, zebrafish has advantageous features as a model animal, such as small size, fertile and easy to breed.  Therefore, it is suggested that zebrafish may be a favored model for the study of BBB permeability.