Abstract
The article aims to present issues arising out of differences in the way that the terms chimera and hybrid are defined in legal systems and by natural sciences in the context of mixing human and animal DNA. The author analyses the different approaches to defining these terms used in various legal systems, dividing them into groups in light of conclusions reached from examining definitions used in natural sciences. The distinction is used to answer the question of which approach to definitions applied by legislators is the best way to handle the subject of human-animal organisms, given the need to balance their impact on medicine and the ethical concerns that arise.