Objective: Attention deficit hyperactivity disorder (ADHD) is considered to be one of the most common childhood psychiatric disorders. The aim of this study was to examine serum levels of total and High Molecular Weight (HMW) adiponectin, and also HMW/total adiponectin ratio with respect to ADHD symptomatology in children. Methods: Serum levels of total adiponectin and HMW adiponectin were measured by commercial enzyme-linked immune-sorbent assay kits in 44 treatment-naïve children with ADHD and age, gender matched 44 healthy controls. ADHD symptoms were scored by Conners Parent Rating Scale-Revised Short (CPRS-RS) and ADHD Rating Scale (ADHD-RS). Body Mass Index-Standart Deviation Scores (BMI-SDS) of all children were evaluated. Results: There were no significant difference in terms of gender, age and BMI-SDS between ADHD and healthy control groups (respectively, p=1, p=0.475, p=0.097). We found that serum total, HMW adiponectin levels and HMW adiponectin/ total adiponectin ratio were significantly lower in ADHD group compared to controls (p [Anadolu Psikiyatri Derg 2020; 21(6.000): 633-640]