Background Caesarean section rates are increasing worldwide, and the long-term effects are unknown. Objective To evaluate the risk of subsequent ectopic pregnancy in women with a previous caesarean section, compared with vaginal delivery. Search strategy Systematic review of the literature using CINAHL, the Cochrane Library, Embase, Medline, PubMed, SCOPUS and Web of Knowledge, published from 1945 until 17 July 2011. Selection criteria Cohort and casecontrol designs reporting on the mode of delivery and subsequent ectopic pregnancy. Two reviewers independently assessed the titles, abstracts, and full articles to identify eligible studies, using a standardised data collection form, and also assessed the study quality. Reference lists of the studies included were also cross-checked. Data collection and analysis Odds ratios (ORs) were combined using a random-effect model to estimate the overall association between caesarean section delivery and the risk of subsequent ectopic pregnancy. Main results Thirteen studies were included, which recruited a total of 61978 women. Five studies reported adjustment for confounding factors, and the pooled OR of subsequent ectopic pregnancy following a caesarean section was 1.05 (95%CI 0.512.15). The removal of one study that reported outlier results yielded a pooled OR of 0.82 (95%CI 0.421.61). The pooled crude OR for all 13 studies was 1.36 (95%CI 0.991.88). Author's conclusions This review found no evidence of an association between prior caesarean section delivery and the occurrence of a subsequent ectopic pregnancy, but the studies included were of poor or variable quality, and only a small number adjusted for potential confounding factors. Further research of a higher methodological quality is required to assess any potential association between mode of delivery and subsequent ectopic pregnancy.