Background: Endometriosis is a chronic inflammatory disease condition that affects an estimated 176 million women worldwide. The disease causes unbearable symptoms of pelvic pain and infertility that limit the quality of reproductive life of affected women. Objective: An attempt has been made to identify certain physiological and/or hormonal factors that may behave as reliable diagnostic markers to assess the various stages of endometriosis. Design: A retrospective population-based study. Material and Methods: Questionnaire-based study was conducted on females of Eastern Uttar Pradesh and Bihar that were suffering from endometriosis. Prevalent patients were characterized in terms of their socio-demographic and clinical characteristics, including validated infertility and chronic disease registries. Results: Progression of the disease was not affected by age and Body Mass Index (BMI) of subjects. The concentration of blood sugar (fasting and PP), and levels of Serum Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), T4, and Thyroid Stimulating Hormone (TSH) did not change as the disease progressed from stage 1 to 4. However, levels of serum estradiol, cortisol, prolactin, T3, and CA-125 increased as endometriosis progressed. There also existed close associations between CA-125, estradiol and cortisol, and stages of endometriosis. Conclusion: Elevated levels of CA-125, estradiol, and cortisol may behave as prominent diagnostic markers to assess the progression of the disease and to discriminate between various stages of endometriosis.