Background: The analysis of hair cortisol concentrations (HairF) is a promising new tool for the assessment of long-term cortisol. With the development of multiple steroid analyses by means of liquid chromatography tandem-mass spectrometry (LC-MS/MS), the analysis of cortisone in hair (HairE) has also been facilitated. However, the influence of various types of determinants on HairF and HairE is still largely unknown. This study systematically assesses the influence of sociodemographic, health, lifestyle, and hair (treatment) characteristics on HairF and HairE. Method: Data of 760 psychiatrically healthy participants (71.8% female, mean age 45.89 years) of the Netherlands Study of Depression and Anxiety (NESDA) were used. HairF and HairE were measured in the proximal 3. cm of scalp hair, using LC-MS/MS. Findings: HairF and HairE strongly correlated. In simple linear regressions, HairF and HairE were higher in older age, in presence of diabetes mellitus, and in men compared to women. More frequent washing of the hair was associated with lower HairF and HairE. Darker hair colours were associated with higher HairF and HairE. An effect of season and of use of oral contraceptives was found for HairF. After full mutual adjustment, only age, presence of diabetes mellitus, hair washing frequency, and season remained significant determinants of HairF. Interpretation: This large-scale study shows that HairF and HairE are upregulated in older age and in the presence of diabetes mellitus. This suggests that these levels are important for somatic health and should be taken into account when using hair corticosteroid analysis in future studies.