PC12 cells are commonly used in the study of neuronal cells. It was reported that IFNgamma enhances neurite outgrowth of PC12 cells by NGF-stimuli. Accordingly, IFNgamma was examined to determine if it could solely produce neurite outgrowth. In addition, because the synergism between TNFalpha and IFNgamma is well-known, this study investigated whether or not a mixture of IFNgamma and TNFalpha might augment neurite outgrowth on PC12 cells. Finally, this study examined how an AG490 treatment, which was used to inhibit the IFNgamma signal in this study, affected the cytokine-mediated phenomenon. The results showed that the cytokines did not cause an increase in apoptosis in the PC12 cells and the serum-starved condition blocked the cytokine-mediated neurite outgrowth. Interestingly, AG490 enhanced this effect. In conclusion, it was shown that IFNgamma has the potential to form neurites, and TNFalpha can enhance this ability.