Objective: To investigate the role of intrahepatic stem/progenitor cells in liver regeneration after the first stage of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS). Methods: Seventy-two SD rats were equally randomized into ALPPS group, portal vein ligation (PVL) group and sham operation group, and then underwent the first stage of ALPPS, PVL alone and sham operation, respectively. The serum levels of transaminases and inflammatory factors and the hepatic regeneration rate (HRR) of the right middle lobe of the liver were determined, and the expressions of cell proliferation index Ki-67 and OV-6, the biomarker of oval cells (stem/progenitor cells), were also examined in each group of rats at postoperative day (POD) 1, 2, 3 and 7, respectively. Results: Compared with sham operation group, the serum levels of transaminases and inflammatory factors were significantly increased in both ALPPS group and PVL group on POD 1 to 2, and their increasing amplitudes in ALPPS group were all significantly higher than those in PVL group (all P<0.05); the HRR of the right middle lobe of the liver and positive Ki-67 rate in the liver tissue were significantly increases in both ALPPS group and PVL group, but the HRR was significantly higher on POD 3 and 7, the positive Ki-67 rate was significantly higher on POD 2 and 3 in ALPPS group than those in PVL group (all P<0.05); obvious OV-6 expression was seen in either ALPPS group or PVL group, but its expression levels in ALPPS group were significantly higher than those in PVL group on POD 2 and 3 (both P<0.05). Conclusion: The first stage of ALPPS is superior to single PVL for inducing liver regeneration, and the mechanism is probably related to higher inflammatory status after ALPPS which may cause the mobilization and activation of the intrahepatic stem/progenitor cells, and thereby promote the rapid liver regeneration.