Hepatocytes in high density are a requisite for the functional performance of complex devices such as bioartificial liver (BAL). In addition to high cell number, efficient mass transfer is also a key parameter in such devices. High-density culture of cells and efficient mass transfer can be achieved in BAL with hollow-fiber-based bioreactors. Even though different types of hollow fibers have been tried in a BAL, prospects of using polypropylene hollow fibers are not well evaluated. In this study, a prototype of bioreactor with polypropylene hollow fibers was fabricated and evaluated for cytotoxicity and hepatocyte function. High density of HepG2/adult hepatocyte cultures was used to evaluate polypropylene hollow fiber to support the biochemical activities (albumin and urea production), ammonia detoxification, and gene expression and to provide effective oxygenation. The results confirmed that a polypropylene hollow-fiber prototype bioreactor is able to provide efficient oxygenation and supported hepatocyte functions in a high-density culture.