BACKGROUND: No study has been conducted to investigate the association between adherence to the EAT-Lancet diet and odds of irritable bowel syndrome (IBS) and functional dyspepsia (FD). This cross-sectional study was aimed to assess the association between adherence to the EAT-Lancet diet and odds of IBS and FD. METHODS: This cross-sectional analysis was done among 1892 Iranian apparently healthy adults, aged 18 to 65 years, in Isfahan, Iran. Usual dietary intakes of participants were assessed using a validated Dish-based, 106-item food frequency questionnaire. To measure participants' adherence to the EAT-Lancet diet, the EAT-Lancet diet index (ELD-I) was calculated. IBS and FD were assessed using ROME IV criteria. RESULTS: In total, 5.29% and 3.17% of participants had IBS and FD, respectively. The mean age of study participants was 39.64 ± 10.24 years, and the mean BMI was 27.08 ± 4.91 kg/m². After adjustment for potential confounding factors, a significant positive association between lower adherence to the EAT-Lancet diet and odds of IBS was revealed (OR: 1.74; 95% CI: 1.00-3.04), but not for FD (OR: 1.37; 95% CI: 0.65-2.89). CONCLUSION: A significant positive association was observed between lower adherence to EAT-Lancet diet and odds of IBS. More prospective studies are needed to affirm these associations.