Purpose Because of the increase in globalization, clinicians all over the world are confronted the questions about safety of Ramadan fasting. However, there is no clear information about whether there is an obstacle for fasting patients with chronic disease. Hence, in the present study, we aimed to investigate the effects of Ramadan fasting on kidney and the factors affecting this relationship in patients with chronic kidney disease. Methods This study involving 117 patients [36 females, 81 males; mean age, 60 (46.0-70.0) years] with stage 2-3 chronic kidney and fasting. Patients were evaluated every 10 days for acute kidney injury (AKI) in Ramadan month. And, patients with acute kidney injury and patients without AKI were grouped. Results When the patients were evaluated for AKI, we observed that in 27 patients had acute kidney injury. While patients without AKI fasted for more days (p < 0.001), urea levels and frequency of hypertension were higher in the group with AKI (p = 0.019;p = 0.025 respectively). We also performed univariate and multiple binary logistic regression analysis to identify the risk factors of AKI. Hypertension and number of fasting day were found to be predictive of AKI (p = 0.02;p < 0.001 respectively). Conclusions We found a significant relationship between hypertension, the number of fasting days and acute kidney injury. Patients with chronic kidney damage and hypertension should be evaluated more carefully, informed about the importance of hydration after fasting and should be followed frequently for AKI.