Background. Obesity is a significant public health problem worldwide. Vitamin deficiencies, developing dueto monotype nutrition, are more likely to be observed in patients than healthy children. The present studyevaluates vitamin and micronutrient levels in children and adolescents with obesity and metabolic syndromecompared to healthy controls. Methods. The study included 73 patients with obesity, 64 patients with metabolic syndrome and 71 healthychildren (control group) aged 10 to 16 years. Physical examinations were performed, and waist circumferenceand systolic blood pressure measurements were recorded. Fasting blood glucose, triglyceride, high-densitylipoprotein cholesterol, low-density lipoprotein cholesterol, total cholesterol, insulin, vitamin A, vitaminE, vitamin B1, vitamin B2, vitamin B6, vitamin B12, folic acid and free carnitine levels were analyzed. Thehomeostatic model of assessment-insulin resistance (HOMA-IR) index was calculated and recorded.Results. The mean age of all patients was 11.9±2.6 years. The serum insulin level and HOMA-IR index werefound to be significantly higher in the obesity and metabolic syndrome groups. No significant difference wasfound between the groups in terms of vitamin A, vitamin B6 and free carnitine levels. Significantly decreasedvitamin E, vitamin B2, vitamin B12 and folic acid and increased vitamin B1 levels were observed in the obesityand metabolic syndrome groups. Conclusions. Compared to healthy children, children with obesity and metabolic syndrome may have varyingdegrees of micronutrient and vitamin deficiency due to poor and unbalanced eating habits. These deficienciesshould also be considered in the treatment and follow-up of obesity and metabolic syndrome