Introduction: Vitamin B12, folate, and iron deficiencies both in early life and later can affect brain development and maintenance via potential mechanisms causing impaired synaptogenesis, myelination and neurotransmission, and increased neurotoxicity and oxidative stress, resulting in neuropsychiatric disorders like cognitive impairment, depression and anxiety. This study aimed to compare serum vitamin B12, folate, and ferritin levels between children and adolescents with anxiety disorders and healthy controls. Materials and Methods: The patient group consisted of 40 children aged 8-17 years who were newly diagnosed with anxiety disorders, had no physical or mental illness other than anxiety disorders, and whose serum vitamin B12, folate, and ferritin levels were measured in the last six months for any reason. As the control group, 40 subjects matched to the patient group for age and sex were selected from mentally and physically healthy children and adolescents. A semi-structured psychiatric interview was used for the diagnosis. Serum vitamin B12, folate, and ferritin levels were obtained from medical records. Results: Serum ferritin and folate levels in the patient group were found to be statistically significantly lower than the controls (34.0 ng/ml versus 46.9 ng/ml, 8.5±2.2 ng/mL versus 10.4±2.8 ng/mL, respectively), unlike serum vitamin B12 levels. Conclusion: Our initial findings may be scientifically important for further studies, which will show that low ferritin and folate levels are associated with childhood anxiety disorders. Whether there is a causal relationship between childhood-onset anxiety disorders and nutritional deficiencies should be investigated in longitudinal studies with larger samples.