ObjectiveTo systematiclly review the correlation between physical activity and the risk of ovarian cancer. MethodsSuch databases as CBM, CNKI, WanFang Data, VIP, The Cochrane Library (Issue 10, 2013), PubMed, EMbase were searched from database establishment to October 2013 to collect prospective cohort studies about physical activities and the risk of ovarian cancer. Relevant magazines and references of included studies were also retrieved. Two reviewers independently screened literature according to the inclusion and exclusion criteria, extracted data, and assessed methodological quality of included studies. Then meta-analysis was performed using RevMan 5.2 software. ResultsA total of 8 cohort studies involving 580 581 subjects, of which there were 2 444 cases of patients with ovarian cancer. The results of meta-analysis showed that, women who participated in moderate level physical activities tended to have a lower incidence of ovarian cancer, compared with those who participated in low level physical activities (age-adjusted:RR=0.87, 95%CI 0.75 to 1.01, P=0.06; multivariate-adjusted:RR=0.97, 95%CI 0.83 to 1.14, P=0.71) but with no significant difference; while women who participated in high level physical activities tended to have a higher incidence of ovarian cancer with a significant difference found in the multivariate-adjusted results (age-adjusted:RR=1.19, 95%CI 0.91 to 1.56, P=0.21; multivariate-adjusted:RR=1.35, 95%CI 1.08 to 1.67, P=0.008). Along with the increase of sedentariness, the incidence of ovarian cancer rose, but with no significant difference. ConclusionCurrent evidence shows that, compared with low level physical activities, high level ones increase the risk of ovarian caner; while the effects of moderate level ones and sedentariness on the risk of ovarian caner still remain uncertain. However, more high-quality studies are required to verify the conclusion of this study because of the limited quantity of the included studies as well as many confounding factors.