Objective: Gastrointestinal symptoms are common in chronic kidney disease (CKD) patients. This situation creates a tendency toward malnutrition. The aim of the current study was to determine the causes of gastrointestinal symptoms and to evaluate their effect on Prognostic Nutritional Index (PNI) and the Controlling Nutritional Status (CONUT) score which are the objective criteria to detect malnutrition. Material and Methods: A total of 66 hemodialysis and 51 peritoneal dialysis patients were included in this study. Patients were divided into two groups. Group I consisted of 26 patients who answered more than 50% of the 16 questions on a gastrointestinal symptoms Likert-type questionnaire as 'frequently' or 'very frequently'. Laboratory and demographic features of patients were recorded. PNI score was calculated using the formula: [10×serum albumin value (g/dL)]+ (0.005×lymphocyte count/mm3). CONUT score was calculated by summing the scores given to certain ranges of total lymphocyte count, albumin, and total cholesterol value. A low PNI and high CONUT score indicates nutritional deficiencies. Result: There was no difference in demographic characteristics between groups. PNI score was lower and CONUT score was higher in Group I. Diabetes mellitus (DM) and CRP-albumin ratio (CAR) were found to be independent risk factors in the development of gastrointestinal symptoms. In multivariate regression analysis, it was observed that DM, non-steroidal antiinflammatory drugs (NSAID) use, and CAR elevation rather than gastrointestinal symptoms affect the CONUT and PNI scores. Conclusion: DM and inflammation play roles in the development of gastrointestinal symptoms. Malnutrition is affected not only by gastrointestinal symptoms but also by underlying additional diseases, some drugs such as NSAID, and inflammation in dialysis patients.