Gene delivery from tissue engineering scaffolds has demonstrated the ability to promote gene transfer and stimulate new tissue formation. In this article we report a novel nanofibrous scaffold based on polyelectrolyte complexes as a vehicle for delivery of DNA. When polycation chitosan (CS) was dropped into polyanion poly(acrylic acid) (PAA) suspension and freeze-dried, CS-PAA nanofibrous scaffold with diverse microstructure would be formed under different experimental conditions. The nanofiber size was affected by the CS molecular weight, the concentration of CS, the volume ratio of CS to PAA, the reaction temperature, the incubation time, and the final pH of the suspension as well. By using adipic acid as branch promoter, adjusting the pH value of the CS solution to 3, and then dropping CS into the PAA solution at a ratio of 3 : 1, a nanofibrous structure with average diameter 140 nm is obtained after the suspension is freeze-dried. These nanofibrous scaffolds were nontoxic and can encapsulate plasmid DNA very well. Transgenic expression in human dermal fibroblasts seeded on the nanofibrous scaffolds was significant after 14 days compared to lipofectamine controls. This result indicates that CS-PAA nanofibrous scaffold have favorable characteristics for nonviral gene delivery to mammalian cell, and have the potential to enhance gene transfer in tissue engineering. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 1769-1780, 2010