Abstract: Objective:To compare the safety and long-term survival of patients with synchronous rectal cancer liver metastasis, who received either simultaneous or staged resection to treat primary tumor and liver metastases.Methods:Clinicopathologic and peri -operative data were collected retrospectively from54patients with synchronous rectal cancer liver metastasis, who received both prima -ry and liver resections between January 2000and April 2015at Peking University Cancer Hospital. Routine follow-up was conducted. The safety and long-term survival of19patients who underwent simultaneous resection were compared with those of 35patients who received staged resection. Results: The clinicopathologic data between the two groups were comparable. Postoperative Clavien-Dindo grades 1, 2, 3, and 4 complications were 10.5% (2/19), 31.6% (6/19), 5.3% (1/19), and 10.5% (2/19) for the simultaneous group, respec -tively, and 8.6% (3/35), 17.1% (6/35), 25.7% (9/35), and 0% (0/35) for the staged group correspondingly, which were not significantly different (P=0.093). However, the median postoperative hospital stay of the simultaneous group was significantly shorter than that of the staged group (14days versus 25days,P<0.001). The median postoperative overall survival (OS) and disease-free survival (DFS) be-tween these groups were not significantly different not reached versus 39months for OS, respectively ( P=0.649); 10months versus 10 months for DFS, respectively (P=0.827). Conclusion:The postoperative complications in simultaneous resection group were not sig -nificantly increased compared with those in staged resection group for synchronous rectal cancer liver metastasis. The long-term results among the groups were similar.