AIM: The aim of this study is to determine the effect of vitamin D replacement therapy on sleep habits in restless legs syndrome (RLS) patients with vitamin D deficiency. METHODS: The study was conducted between September 1, 2018, and September 1, 2019, at the Pediatrics outpatient clinic of Bezmialem Vakif University. 46 cases with RLS and 43 healthy controls between these dates were included in the study. The Children's Sleep Habits Questionnare was filled out retrospectively by parents. RESULTS: While vitamin D supplementation was given to 20 children with RLS who were found to have vitamin D deficiency, the 26 patients without vitamin D deficiency did not receive supplementation. There was no significant difference between the treatment groups in terms of gender, age, and pre-treatment sleep habits. Compared to the pre-treatment period, post-treatment bedtime resistance, sleep onset delay, sleep anxiety, parasomnias, daytime sleepiness, and CSHQ total score were significantly improved in RLS cases with vitamin D deficiency. There were no significant differences in RLS patients without vitamin D supplementation. Other comparisons also showed no difference between groups. CONCLUSION: There was no difference between the sleep habits of RLS cases with and without vitamin D deficiency. Sleep habits improved positively after vitamin D supplementation in patients with vitamin D deficiency compared to the pre-treatment period. There was no difference in the sleeping habits of RLS patients without vitamin D deficiency during the same period. Vitamin D supplementation can improve sleep habits in patients with RLS.