We report here that by good design, polyaniline (PANI) can be cytocompatible and formed into usable scaffolds for bio-medical applications. By adjusting the ratio of two monomers, aniline (AN) and metanilic acid (MA), a series of copolymers with different sulfonation degrees have been synthesized. Four-probe conductivity measurements showed that as the sulfonation degree increased, the conductivity decreased. XPS analysis was used to determine the sulfur/nitrogen ratio. In vitro cell culture study was conducted with human osteosarcoma (Has) cells. Microscopic observation did not show abnormal cellular behavior when sulfonated polyaniline (SPAN) was put in direct contact with HOS cells. Cells growing on the non-transparent dark green SPAN films were observed with fluorescence by laser scanning cytometry (LSC). In proliferation studies more than 70% of cells were found viable on SPAN compared to 88% for poly(L-lactic acid) with the number of cells growing on glass as a control, indicating generally good biocompatibility. We expect these polymers would have great potential in biological applications of conducting polymers as we determine that a variety of physical and chemical properties can be controlled through synthesis.