Objectives: Many studies show that adrenomedullin (ADM) is associated with nitric oxide (NO) and various mechanisms and is involved in the etiopathogenesis of schizophrenia, bipolar disorder and autism by oxidative stress and HPA axis dsyregulation. The aim of this study comparison of nitric oxide and adrenomedullin levels in children with ADHD, AD and healthy control included in our study, especially due to their effect mechanisms as they may predict anxiety symptom, was to investigate the relationship between nitric oxide and adrenomedullin levels and anxiety symptoms in children with ADHD, AD and healthy control. Methods: The study included 27 ADHD, 27 AD and 23 healthy children without any previous drug use, without comorbid disease. The semi-structured interview was conducted by the researcher in all the children attending the study. Sociodemographic information form, Conner’s Parent and Teacher Rating scale and State-Trait Anxiety Inventory (STAI) were evaluated. NO level measured by spectrophotometer, ADM levels were measured by ELISA. Results: There was no statistically significant difference in the serum NO and ADM levels of the children included in the sampling group according to age and sex. There was no statistically significant difference between NO and ADM levels between ADHD, AD and control groups. There was no statistically significant relationship between serum NO and ADM levels and ADHD, AD and control group children of state-trait anxiety scores. Conclusions: These findings may suggest that NO and ADM levels in children with ADHD, AD do not show these diseases and that these parameters are not associated with anxiety symptoms.