BACKGROUND: Bone turnover markers (BTMs) are widely used tool for monitoring the response to osteoporosis therapy, and the normal adult reference range is the baseline value for the treatment of osteoporosis with anti-resorptive agents. This study was aimed to establish age- and sex-specific reference ranges of serum osteocalcin and serum type I collagen C-telopeptide (S-CTX) in adults based on menstrual stage. METHODS: Serum osteocalcin, S-CTX and bone mineral density (BMD) were measured in 291 adults (men: 162, women: 129), and follicle stimulating hormone (FSH) in women. Seven women whose serum FSH levels were >30 IU/mL were categorized as perimenopausal despite their regular menses. RESULTS: Among females with normal BMD, there were no difference in serum osteocalcin and S-CTX levels between premenopausal and postmenopausal women. Females with osteopenia in pre- and postmenopausal stage showed higher serum osteocalcin and S-CTX levels than females with normal BMD. For subjects with normal BMD, reference ranges of serum osteocalcin and S-CTX were 6.4~21.6 ng/mL and 0.08~0.85 ng/mL for 30~59-year-old females. For males with normal BMD, reference ranges of serum osteocalcin were 10.1~24.3 ng/mL for 30~39 years old and 7.7~22.4 ng/mL for 40~59 years old, and reference range of CTX was 0.13~1.27 ng/mL for 30~59 years old. CONCLUSIONS: This study will provide a redefinition of the criteria required in order to establish the normal reference ranges for BTMs. Moreover, we believe that our data will come in handy when used as normal reference ranges of BTMs in premenopausal women.