Background In theory, infections that arise after female genital mutilation (FGM) in childhood might ascend to the internal genitalia, causing in?ammation and scarring and subsequent tubal-factor infertility. Our aim was to investigate this possible association between FGM and primary infertility. Methods We did a hospital-based case-control study in Khartoum, Sudan, to which we enrolled women (n=99) with primary infertility not caused by hormonal or iatrogenic factors (previous abdominal surgery), or the result of malefactor infertility. These women underwent diagnostic laparoscopy. Our controls were primigravidae women (n=180) recruited from antenatal care. We used exact conditional logistic regression, stratifying for age and controlling for socioeconomic status, level of education, gonorrhoea, and chlamydia, to compare these groups with respect to FGM. Findings Of the 99 infertile women examined, 48 had adnexal pathology indicative of previous in?ammation. After controlling for covariates, these women had a signi?cantly higher risk than controls of having undergone the most extensive form of FGM, involving the labia majora (odds ratio 4·69, 95% CI 1·49–19·7). Among women with primary infertility, both those with tubal pathology and those with normal laparoscopy ?ndings were at a higher risk than controls of extensive FGM, both with borderline signi?cance (p=0·054 and p=0·055, respectively). The anatomical extent of FGM, rather than whether or not the vulva had been sutured or closed, was associated with primary infertility. Interpretation Our ?ndings indicate a positive association between the anatomical extent of FGM and primary infertility. Laparoscopic postin?ammatory adnexal changes are not the only explanation for this association, since cases without such pathology were also affected. The association between FGM and primary infertility is highly relevant for preventive work against this ancient practice.