BACKGROUND: We aimed to determine the knowledge and attitudes of Turkish pediatricians concerning vitamin D supplement. METHODS: The study was planned cross-sectional to be carried out between April-May 2015 in Turkey. A questionnaire form that determined the participants' opinions and practices concerning vitamin D supplement was completed via face-to-face interview. RESULTS: A total of 107 pediatricians (49.3%) and 110 pediatric residents (50.7%) participated in the study. Of the physicians, 85.2% recommended vitamin D supplement for all infants and children regardless of diet, 13.4% recommended for the infants which are solely breastfed. Vitamin D supplement is recommended at a dose of 400 IU/day by 88.8% of pediatricians and by 90% of pediatric residents. Of the pediatricians and pediatric residents, 72% and 68.2%, respectively commence vitamin D supplement when the newborn is 15 days old. The rates of recommending vitamin D supplement until the age of one and two years were higher among pediatricians (48.6% and 41.1%, respectively) than pediatric residents (40.9% and 32.7%, respectively). The rate of starting vitamin D supplement for fontanelle closure was significantly higher among pediatric residents (15.5%) than pediatricians (3.7%) (p = 0.002). It was determined that the rate of prescribing vitamin D supplement until fontanelle closure was higher among pediatric residents (18.2%) than pediatricians (0.9%). CONCLUSIONS: The present study suggest that the knowledge of pediatricians about recommendation of vitamin D needs to be enhanced by education programs in addition to free vitamin D supplement provided by the Ministry of Health.