Background: Osteoporosis is characterized by demineralization of bones and it is a complication of women in post-menopausal life. Bone alkaline phosphatase is an isoenzyme of alkaline phosphatase which helps in the mineralization of bones and it is heat labile in nature. Its measurement facilitates the clinical diagnosis of Osteoporosis. Objectives: To assess the status of total alkaline phosphatase and heat-labile isoenzyme fraction (bone fraction) in serum of pre and post-menopausal women and to relate the findings to the clinical condition /final diagnosis to make out the correlation between the pre and postmenopausal women. Methodology:A total of 70 subjects, consisting of 35 pre-menopausal women (38.11 ± 4.3 years of age) and 35 post-menopausal women (54.40 ± 4.6 years) were constituted for the study. Their total alkaline phosphatase was measured directly and the heat stable alkaline phosphatase was measured after heating the serum at 56℃ for 10 minutes. Spectrophotometric P- Nitro-Phenyl Phosphate method was followed for the estimation. Heat labile alkaline phosphatase levels were obtained by subtracting the heat stable fraction from total Alkaline phosphatase. Result: The measured serum total alkaline phosphatase level was slightly increased in post menopause compared to premenopausal women but it was not statistically significant. The levels of heat-labile Alkaline phosphatase showed significant difference between pre and post-menopausal women by ***: p < 0.01: ***: p < 0.001 respectively. Conclusion: Heat labile alkaline phosphatase can be used as a biomarker to diagnose Osteoporosis in post-menopausal women.