Context Obesity and cardiometabolic diseases are associated with higher long-term glucocorticoid levels, measured as scalp hair cortisol (HairF) and cortisone (HairE). Cardiometabolic diseases have also been associated with copeptin, a stable surrogate marker for the arginine-vasopressin (AVP) system. Since AVP is, together with corticotropin-releasing hormone (CRH) an important regulator of the hypothalamic-pituitary adrenal axis (HPA axis), we hypothesize that AVP contributes to chronic hypercortisolism in obesity. Objective To investigate whether copeptin levels are associated with Higher HairF and HairE levels in obesity. Design A cross-sectional study in 51 adults with obesity (BMI ≥30 kg/m²). Methods Associations and interactions between copeptin, HairF, HairE, and cardiometabolic parameters were cross-sectionally analyzed. Results Copeptin was strongly associated with BMI and waist circumference (WC) (rho = 0.364 and 0.530, P = 0.008 and <0.001, respectively), also after correction for confounders. There were no associations between copeptin and HairF or HairE on a continuous or dichotomized scale, despite correction for confounders. Conclusion In patients with obesity, AVP seems not a major contributor to the frequently observed high cortisol levels. Other factors which stimulate the HPA axis or affect cortisol synthesis or breakdown may be more important than the influence of AVP on long-term glucocorticoid levels in obesity.