Thymosin alpha 1 (Tα-1) is a naturally occurring substance synthesized by the thymus tissue, known to activate various immune system cells. It has been reported to increase the production of Natural Killer cells, CD4 and CD8 cells, and cytokines such as IL-2, IL-3, and IFNγ. Furthermore, it plays a vital role in regulating immunity, inflammation, and tolerance. Its effect on the immune system is exerted via its modulatory action on innate immune system cells, thereby functioning as an endogenous regulator for both inflammatory and adaptive immune systems. In this study, we sought to evaluate the cytological and anti-inflammatory effects of Tα-1 on RAW 264.7 cells. The cytological effects of Tα-1 were assessed using the MTT assay, with the IC50 value against RAW 264.7 cells determined to be 368.105 ug/ml. The morphological observations made at various concentrations of Tα-1 showed increased cytotoxicity and decreased cell density of RAW 264.7 cells with increasing test concentration. Furthermore, the anti-inflammatory effects of Tα-1 were evaluated by analyzing the nitric oxide (NO) production in RAW 264.7 cells. Treatment with the test items at concentrations ranging from 7.813 to 31.25 ug/ml showed a dose-dependent reduction in NO production compared with the control group. These findings suggest that Tα-1 may have the potential as an anti-inflammatory agent in the treatment of various diseases associated with inflammation.