A chimeric non-human animal having an in vivo human hepatocyte population,wherein the effects of non-human animal cells on drug metabolism aresuppressed ordeleted is provided. A method for producing a chimeric non-human animal thatlacks adrug-metabolizing system or has a suppressed drug-metabolizing system and isprovidedwith a drug-metabolizing system driven by human hepatocytes, is provided. Themethod comprises transplanting human hepatocytes into a non-human animalcharacterized by (i) being immunodeficient, (ii) having liver damage, and(iii) lackingthe functions of an endogenous Cyp3a gene.
