Background: Nephrolithiasis is a global health problem that is growing exponentially in the developed and developing countries. This study aimed to determine the dietary diversity score (DDS) and its association with nutrient adequacy in patients with calcium oxalate kidney stone. Methods: The present cross-sectional study was conducted on 276 male patients with calcium oxalate kidney stone. The validity and reliability of dietary intake was assessed by the 147-item food frequency questionnaire. Based on the USDA Food Guide Pyramid, the five food groups (grains, vegetables, fruits, meats, and dairy products) were used to determine the DDS. The nutrient adequacy ratio and the mean adequacy ratio were calculated using the Recommended International Standards. Results: The mean of the body mass index of the participants was 27.49 ± 4.01 kg/m². Mean of the total DDS was also 5.62 ± 1.29. Participants in the highest DDS tertile had higher energy and fat intake than those in the lowest tertile (P-trend < 0.05). The highest and lowest DDS were observed in the fruit and vegetable groups: 1.58 ± 0.53 and 0.91 ± 0.29, respectively. The total DDS had a positive correlation with the adequacy of energy intake and macronutrients including protein and fats (P < 0.05). Furthermore, a significant positive correlation was found between the total DDS and the mean adequacy ratio (P < 0.01, r = 0.2). Conclusion: The findings showed that patients with calcium oxalate kidney stone did not have an appropriate level of total DDS (DDS < 6), indicating that they did not receive diverse nutrients.