ObjectivesTo systematically review the relationship between cadmium exposure and the risk of hypertension.MethodsPubMed, EMbase, The Cochrane Library, CBM, WanFang Data, VIP and CNKI databases were searched online to collect studies of cadmium exposure and hypertension from inception to March 2018. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Meta-analysis was then performed by Stata 12.0 software.ResultsA total of 9 studies were included, of which 19 841 cases were patients of hypertension, and 27 578 cases were in the control group. The results of meta-analysis showed that blood cadmium was associated with risk of hypertension (OR=1.23, 95%CI 1.17 to 1.30, P<0.001). However, no significant association was found between urinary cadmium and the risk of hypertension (OR=0.77, 95%CI 0.55 to 1.07,P=0.61). The results of subgroup analysis showed non-smokers (OR=1.19, 95%CI 1.09 to 1.31, P<0.001), males (OR=1.19, 95%CI 1.11 to 1.28,P<0.001), females (OR=1.28, 95%CI 1.18 to 1.40,P<0.001), yellow race (OR=1.26, 95%CI 1.19 to 1.34,P<0.001), and the literatures published after 2010 (OR=1.24, 95%CI 1.17 to 1.31,P<0.001) were associated with risk of hypertension in blood cadmium. The current smokers (OR=0.72, 95%CI 0.56 to 0.93,P=0.013), yellow race (OR=0.65, 95%CI 0.50 to 0.83, P=0.001), and the literatures published before 2010(OR=0.61, 95%CI 0.50 to 0.75, P<0.001) were associated with risk of hypertension in urinary cadmium.ConclusionsBlood cadmium is associated with risk of hypertension and high level of blood cadmium is a risk factor for hypertension. The levels of blood cadmium of non-smokers, males, females, yellow race are associated with risk of hypertension in blood cadmium. Urinary cadmium was not significantly associated with the risk of hypertension. The above conclusions are required to be verified by more high quality studies.