Background/Aims: Inflammatory bowel disease (IBD) is a complex condition precipitated by genetic susceptibility and possibly a disturbed microbiome. The role of dairy foods in IBD is controversial. This study examined the association between lactose intolerance (LI) and IBD. Methods: Data on hospital admissions of all IBD adult patients were extracted from the National Inpatient Sample database between 2004 and 2014. The comorbidities and outcomes of interest were defined by querying all the diagnostic and procedural fields for the corresponding International Classification of Diseases 9th version (ICD-9) codes. Patients with IBD were defined as the “study group,” and the patients who did not have IBD were defined as the “control group”. LI was identified in both groups using the ICD-9 codes. Multivariate logistic regression was performed to examine the association between IBD and LI. Results: The total population was 71,342,237 patients, of which 598,129 (0.83%) had IBD. The IBD patients were younger (52 years vs. 57 years) and with fewer females (57.5% vs. 60.1%) (p<0.001 for all). After adjusting for the potential confounding factors, the IBD group had a significantly higher rate of LI (OR 2.71, 95% CI 2.55-2.88, p<0.001) compared to the non-IBD group. The findings were similar on the further stratification of IBD into Crohn’s disease compared to the control group (OR 2.70, 95% CI 2.50-2.92, p<0.001) and ulcerative colitis compared to the control group (OR 2.71, 95% CI 2.46-2.98, p<0.001). Conclusions IBD patients have a 2.7 times higher risk of LI. Screening for LI in this population is warranted to avoid confusing or overlapping symptomatology.