Background: Striae distensae (SD) is a common skin disorder in the form of linear atrophy, which arises due to stretching and is one of the most common cosmetic problems. There is no scoring system to assess the severity of striae distensae that is easy to use, non-invasive, and consistent and can be used to evaluate SD treatment. This study formulated and validated a scoring system to assess the severity of striae distensae. Methods: This study was a descriptive observational study with a cross sectional approach involving 30 female health workers at the Universitas Sumatra Utara Hospital. Assessment of SD severity in six regions using four parameters. Results: A scoring system for the severity of striae distensae has been formulated, named the INA score, to assess the severity of SD in six regions; mammae, axilla, abdomen, femur, gluteus and poplitea using four parameters; the number of lines, the size of the longest striae distensae line, color, and itchy. The results of the validation test are statistically valid (r-value>0.361), and the reliability test is found to be reliable (Cronbach's Alpha>0.361). Conclusion: The formulation of a valid and reliable scoring system, named the INA score, has been obtained to assess the severity of striae distensae measured at six locations and four parameters.