Polyaniline (PANi) films were prepared by direct polymerizing deposition with four different kinds of acids as dopants or were prepared by a casting method on the surface of a polytetrafluoroethylene substrate. The properties of PANi films were characterized using atomic force microscopy, electrical conductivity measurements, and water contact angle measurements. Unlike the casting PANi film, experimental results indicated that the synthesized PANi films had a similar nanostructure as that of average nanoparticles (approximate diameter of 30-50 nm). To investigate the potential usefulness of PANi films in biomedical applications, we also studied their biocompatibility through the adhesion and proliferation properties of PC-12 pheochromocytoma cells. All the films were found to be biocompatible and allowed cell attachment and proliferation. However, the synthesized films have a much higher ability for cell adhesion than the casting film. After 4 days of culture on different PANi films, the cells formed more confluent monolayers on the synthesized PANi films than on the casting films. These results demonstrate that the PANi films could be used to culture neurotic cells and that their surface architecture on the nanoscale may affect cell function such as attachment and proliferation.