Patients with 21-hydroxylase deficiency (21-OHD) are at risk of reduced bone mineral density (BMD) and fracture due to long-term glucocorticoid treatment. Trabecular bone score (TBS) is complementary to conventional BMD as a marker for bone quality in patients with glucocorticoid induced osteoporosis. The purpose of this study is to evaluate the BMD and TBS in a cohort of patients with 21-OHD and analyze factors related to TBS.An observational study.A total of 46 21-OHD adult patients treated with glucocorticoid for over 10 years who visited Peking Union Medical College Hospital between 2015 and 2019 were recruited. Eight male patients included in this study were all under 50 years old, and 38 female patients were all premenopausal.Diagnosis was confirmed by multiplex ligation dependent probe amplification combined with sequencing. Data were collected on physical characteristics, serum hormones, and glucocorticoid treatment. Skeletal quality was evaluated by BMD and TBS, and factors related to TBS were analyzed.Among the 46 patients, 2 (4.3%) had low BMD (Z-score ≤-2), while 11 (23.9%) patients had low TBS (degraded or partially degraded microarchitecture). The proportion of bone abnormality evaluated by TBS was higher than that by BMD (p<0.001). Patients with lower TBS had significantly higher daily hydrocortisone dosage (p=0.009 for males; p=0.019 for females). TBS value was negatively correlated with daily hydrocortisone dosage (r=-0.317, p=0.026), and positively correlated with BMI in female patients (r=0.345, p=0.034). And there was a negative correlation between TBS value and the current age in male patients (r=-0.741, p=0.036). The distribution of genotypes (p=1.000 for male; p=0.567 for female) or phenotypes (p=0.486 for male; p=0.075 for female) had no statistical difference in patients with normal or abnormal TBS.Approximately 24% of patients with 21-OHD had abnormal microarchitecture of their bone in our study, and TBS score was negatively correlated with daily glucocorticoid dosage in patients. TBS may be used alongside conventional BMD as a complementary marker for bone evaluation in 21-OHD patients.