Mutations in the gene encoding 21-hydroxylase cause the most common form of congenital adrenal hyperplasia (CAH) [1,2]. Clinical management aims at replacement therapy with glucocorticoids and mineralocorticoids to correct hypocortisolism, hypoaldosteronism and to normalize hyperandrogenism, which often results in higher glucocorticoid doses than in primary adrenal insufficiency (PAI) [3]. Physicians face the problem to adjust to ideal dosage of glucocorticoids in order to avoid under-as well as overtreatment [4,5]. Undertreatment may result in higher risk of adrenal crisis, disturbed pubertal development, reduced final height, infertility, and androgen-driven insulin resistance, however overtreatment results in obesity, impaired glucose homeostasis, infertility and reduced bone mineral density (BMD) [1]. However, the best regimen and approach to Improvement of health-related quality of life in adult women with 21-hydroxylase deficiency over a seven-year period Adjustment for age and sex was performed by transformation of score values into age-and sex-adjusted Z-scores using data sets from respective normative groups. Data regarding glucocorticoid therapy, clinical and hormonal parameters were assessed. We found that two of eight scales of SF-12 showed a significant improvement and four of eight scales a positive trend to better scores. No significant changes were seen in scores for HADS or for steroid hormone levels. Daily hydrocortisone equivalent dose per body surface significantly decreased over the study period. No changes in BMI were observed over the study period. We conclude that improvement of HRQoL in adult female 21-OHD patients is possible. Several factors might be involved in this improvement including reduced daily hydrocortisone equivalent dose per body surface.