OBJECTIVES: The bone mineral density (BMD) of young aged women was not fully investigated because of the limited indication of BMD test. This study was to investigate mean Z-score of BMD in healthy young aged Korean women and to find out factors influencing the BMD score in her twenties and thirties. METHODS: A total 876 young aged (20-40 years) women who had taken dual energy X-ray absorptiometry (DXA) for BMD screening from 2010 to 2014 were analyzed retrospectively using demographic data including body mass index (BMI), waist circumference (WC), thyroid stimulating hormone (TSH), and serum lipid profile. We compared the two age groups, in her twenties and thirties, regarding BMD and other parameters. RESULTS: The mean age was 34.5±0.44 (years) and mean height, weight, BMI were 162.82±0.06 (cm), 55.28±0.24 (kg), 20.84±0.81 (kg/m2). Mean Z-score of bone mineral density of lumbar spine L 1-4 (BMD-L) and femoral hip (BMD-F) were 0.17±0.94 and -0.19±0.85. Mean TSH level was 2.49±0.78 (mIU/L). All serum lipid parameters were significantly worsen in women in her thirties than in her twenties. The pattern of correlation between TSH and BMD was different according to the age group. That is, mean Z-score of BMD was positively correlated with TSH in her twenties and this relationship was gradually changed to a negative correlation in her thirties. CONCLUSION: Mean Z- score of BMD-L and BMD-F adjusted for BMI among young Korean women were 0.17±0.94 and -0.19±0.85, respectively. TSH had a positive correlation with BMD among women in her twenties.