Primary rat hepatocytes are a widely used experimental model to estimate drug metabolism and toxicity. In currently used two-dimensional (2D) cell culture systems, typical problems like morphological changes and the loss of liver cell-specific functions occur. We hypothesize that the use of polymer scaffolds could overcome these problems and support the establishment of three-dimensional (3D) culture systems in pharmaceutical research. Isolated primary rat hepatocytes were cultured on collagen-coated nanofibrous scaffolds for 7 days. Cell loading efficiency was quantified via DNA content measurement. Cell viability and presence of liver-cell-specific functions (albumin secretion, glycogen storage capacity) were evaluated. The activity of liver-specific factors was analyzed by immunofluorescent staining. RNA was isolated to establish quantitative real-time PCR. Our results indicate that primary rat hepatocytes cultured on nanofibrous scaffolds revealed high viability and well-preserved glycogen storage. Albumin secretion was existent during the entire culture period. Hepatocytes remain HNF-4 positive, indicating highly preserved cell differentiation. Aggregated hepatocytes re-established positive signaling for Connexin 32, a marker for differentiated hepatocyte interaction. ZO-1-positive hepatocytes were detected indicating formation of tight junctions. Expression of cytochrome isoenzymes was inducible. Altogether the data suggest that nanofibrous scaffolds provide a good in vitro microenvironment for neo tissue regeneration of primary rat hepatocytes. Biotechnol. Bioeng. 2011;108: 141-150. (C) 2010 Wiley Periodicals, Inc.