BACKGROUND: Despite the fact that dietary intakes are suggested to affect fecundity and reproductive outcomes, data about the favorable impacts of dietary quality indicators on diminished ovarian reserve (DOR) is scarce. So, we aimed to examine the relationship between the Dietary Approaches to Stop Hypertension (DASH) score and odds of DOR. METHODS: This case-control study was conducted among 370 women (120 with DOR as the case group and 250 with normal ovarian reserve as the control group). Cases and controls were frequency-matched according to age and body mass index (BMI) at the study-design stage. Dietary information derived from a validated semi-quantitative food frequency questionnaire (FFQ) was used to count energy-adjusted DASH score based on eight components. Markers of ovarian reserve, including anti-Müllerian hormone (AMH) and antral follicle count (AFC) which were measured in serum samples and by transvaginal ultrasound, respectively. The multivariable-adjusted binary logistic regression was used to identify the association between energy-adjusted DASH score and odds of DOR. RESULTS: Higher energy-adjusted DASH score was related to lower diastolic blood pressure (DBP) in women with DOR (p = 0.006). No statistically significant association was observed between DASH adherence and the odds of DOR. In the crude model, compared with the lowest tertile (T1), the odds ratios for DOR were 0.87 (95% CI: 0.51-1.49) for T2 and 0.78 (95% CI: 0.46-1.33) for T3 (P-trend = 0.370). After adjustment for potential confounders, the association remained non-significant in Model 1 (T2: 0.93, 95% CI: 0.53-1.63; T3: 0.76, 95% CI: 0.43-1.33; P-trend = 0.328) and Model 2 (T2: 0.88, 95% CI: 0.49-1.56; T3: 0.74, 95% CI: 0.42-1.30; P-trend = 0.288). Nevertheless, in an exploratory unadjusted analysis among women with DOR, AFC differed significantly across energy-adjusted DASH tertiles, with higher AFC observed among women in the higher DASH adherence categories (p = 0.015). CONCLUSIONS: Higher adherence to the DASH dietary pattern was not significantly associated with the odds of DOR. Further prospective studies are warranted to clarify the potential relationship between dietary patterns and ovarian reserve.