BACKGROUND AND AIMS: The relationship between vitamin D-deficiency and pathogenesis of non-alcoholic fatty liver diseases (NAFLD) has been always a controversial subject. The present study is aimed to investigate the effects of vitamin D on the reduction of liver enzymes and, then, compare its effects with those of diet and physical activities individually. PATIENTS AND METHODS: The present double-blinded randomized clinical trial was conducted at …..University of Medical Sciences in 2017. For this purpose, 80 patients with NAFLD and vitamin D-deficiency were randomly divided into two groups, namely intervention and control. Subsequently, the patients in both groups were provided with programs of diets and physical activities. The patients in the intervention group received, in addition to the given treatment, the vitamin at the dosage of (VIT-D/50000 unit) once per week for ten weeks. Afterwards, the data related to the clinical and demographic characteristics of both groups were collected and, then, compared with each other using statistical methods. RESULTS: The applied therapeutic interventions led to a significant reduction in the variables including AST, ALT, total cholesterol, and LDL-C in both groups (p < 0.05). As for the two indices of blood sugar and triglyceride, the control group exhibited significantly less variations (p < 0.05). C O N C L U S I O N: The obtained results showed that the administration of vitamin D had no considerable superiority over the diet and physical activities in terms of reducing the liver enzymes as well as other investigated parameters.