The physiological roles of the protease inhibitor SERPINB3 (SB3) are still largely unknown. The study was addressed to assess the biological effects of this serpin in vivo using a SB3 transgenic mouse model. Two colonies of mice (123 transgenic for SB3 and 148 C57BL/6J controls) have been studied. Transgenic (TG) mice showed longer survival than controls and the difference was more remarkable in males than in females (18.5% vs 12.7% life span increase). In TG mice decreased IL-6 in serum and lower p66shc in the liver were observed. In addition, TG males showed higher expression of mTOR in the liver. Liver histology showed age-dependent increase of steatosis and decrease of glycogen storage in both groups and none of the animals developed neoplastic lesions. In conclusion, the gain in life span observed in SB3-transgenic mice could be determined by multiple mechanisms, including the decrease of circulating IL-6 and the modulation of ageing genes in the liver.