Objective To investigate the incidence rate,timing and risk factors of metachronous pulmonary metastasis after curative resection in patients with rectal cancer.Methods A total of 198 patients with rectal cancer undergoing curative resection in gastroenterology surgery department of Beijing Hospital from 2007 to 2012 were enrolled in this retrospective study.The metachronous metastasis and recurrence were observed.Clinicopathologic factors which might be associated with postoperative pulmonary metastasis were analyzed by the univariate and multivariate analysis.Results The 5-year disease-free survival was 76.8％ in a total of 198 patients cohort.The most frequent metastatic sites were the lung(incidence of 11.6 ％)followed by liver(7.6 ％).Median interval from rectal surgery to diagnosis of pulmonary metastasis was much longer than that of hepatic metastasis(19 vs.11 months,P =0.002).Tumor location,current tumor-node-metastasis (TNM)stage,and a positive circumferential resection margin(CRM)were identified as the independent risk factors for pulmonary metastasis.The most common metachronous metastasis site for rectal cancer after curative surgery was the lung in elderly patients.Conclusions The lung is the most common metachronous metastatic site after curative surgery of rectal cancer in elderly patients.For patients with unfavorable risk profiles,a more intensive surveillance program is needed for the early detection of metachronous metastasis and recurrence.