© 2021 Turkish Society of Nephrology. All rights reserved.Objective: This study aimed to assess whether the administration of L-carnitine (LC) was effective on the cognitive function of patients on hemodialysis (HD). Materials and Methods: Results of 33 patients who received 1000 mg of LC intravenously thrice a week for 6 months and 40 patients who did not receive LC were assessed. The mini-mental state exam (MMSE) was used to assess the cognitive function. An MMSE score of <24 was considered to be a cognitive impairment (CI). Results: The rate of CI was 42.5% in patients on HD. The MMSE score of patients who had received LC was higher than those who did not (24.79±3.577 and 22.70±5.341, respectively, p=0.046). The MMSE score of men was higher than women (24.74±4.374 and 21.78±4.766, respectively, p=0.009). The MMSE score was significantly lower in patients with diabetes than in those without diabetes (20.69±6.343 and 24.47±3.822, respectively, p=0.004). It was demonstrated in the multiple general linear model analysis that age (p<0.001), sex (p<0.001), diabetes (p=0.010), total carnitine (p=0.005), and free carnitine (p=0.003) were independent factors affecting the MMSE scores. Conclusion: These findings suggest that regular follow-up of serum carnitine levels and replacement of LC could be positive factors in improving cognitive function in patients on HD.