BACKGROUND & AIMS: We examined the risk of cervical neoplasia (dysplasia or cancer) in women with ulcerative colitis (UC) or Crohn's disease (CD). We also calculated the reverse, the risk for diagnosis with cervical neoplasia before development of inflammatory bowel disease (IBD). METHODS: We established a national cohort of women diagnosed with UC (n = 18,691) or CD (n = 8717) between 1979 and 2011 and a control cohort of individually matched women from the general population (controls, n = 1,508,334). Incidence rate ratios (IRRs) of screening activity and diagnosis of cervical neoplasia in women with IBD were assessed by Cox proportional hazards regression analysis. Odds ratios (ORs) of cervical neoplasia before diagnosis of IBD were calculated by using conditional logistic regression. RESULTS: Women with CD underwent cervical cancer screening as often as women in the general population (IRR, 0.99; 95% confidence interval [CI], 0.96-1.02), whereas screening frequency was slightly increased in women with UC (IRR, 1.06; 95% CI, 1.04-1.08). A total of 561 patients with UC were diagnosed with dysplasia during a median follow-up time of 7.8 years, and 28 patients with UC developed cervical cancer, compared with 1918 controls. A total of 407 patients with CD were diagnosed with dysplasia during a median follow-up time of 8.3 years, and 26 patients with CD developed cervical cancer, compared with 940 controls. Patients with UC had increased risk of low-grade (IRR, 1.15; 95% CI, 1.00-1.32) and high-grade (IRR, 1.12; 95% CI, 1.01-1.25) squamous intraepithelial lesions (SILs), whereas patients with CD had increased risks of low-grade SIL (IRR, 1.26; 95% CI, 1.07-1.48), high-grade SIL (IRR, 1.28; 95% CI, 1.13-1.45), and cervical cancer compared with controls (IRR, 1.53; 95% CI, 1.04-2.27). ORs for cervical cancer were also increased 1-9 years before diagnosis of UC, compared with women without UC (OR, 2.78; 95% CI, 2.12-3.64) or CD (OR, 1.85; 95% CI, 1.08-3.15). CONCLUSIONS: In a population-based nationwide cohort study, we found a 2-way association between IBD, notably CD, and neoplastic lesions of the uterine cervix. This observation is not explained by differences in screening activity.