Background: Primary amenorrhea, defined as the absence of menarche by age 15 in the presence of secondary sexual characteristics or by age 13 without them, arises from various etiologic factors. Timely diagnosis and targeted interventions, including genetic counseling and reconstructive surgeries, are essential for effective management. Aim of the study: The aim of this study was to prevalence of etiologic causes of primary amenorrhea among women in a tertiary care center. Methods: This cross-sectional study was conducted in Department of Obstetrics and Gynaecology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh, during the period from June 2023 to May 2024. Total 120 women presenting with primary amenorrhea during the study period were included. Result: The study involved participants with a mean age of 17.8 ± 3.2 years, with 58.3% aged 15-20. Most were from low-income backgrounds (62.5%), and 33.3% reported parental consanguinity. Hormonal causes (41.7%) predominated, followed by structural (33.3%) and genetic causes (16.7%). Hypogonadotropic hypogonadism (60.0%) and Müllerian agenesis (62.5%) were leading subtypes, while Turner syndrome accounted for 60.0% of genetic cases. Diagnostic findings included pelvic ultrasound abnormalities (45.8%, p <0.001) and karyotype abnormalities (16.7%). Hormonal imbalances were most common (58.3%), reflecting the diversity of etiologies and the importance of advanced diagnostics in identifying underlying causes. Socioeconomic status and parental consanguinity significantly influenced etiological patterns. Conclusion: This study highlights significant associations between socio-demographic factors, such as age, consanguinity, socioeconomic status, and etiological categories were observed. Diagnostic findings underscored the importance of pelvic ultrasound, karyotyping, and hormonal evaluation in accurate classification.