Abstract Background: Approximately 10%–25% of women are affected with abnormal uterine bleeding (AUB). It is essential to have a thorough understanding and knowledge about the disease, causative factors, pathophysiology, incidence and prevalence of various causative factors, clinical presentations, and diagnostic aids for an early prediction and diagnosis of disease to treat the condition at the earliest possible phase and with minimum morbidity and costs. Objective: The objective of this study was to study the causes of AUB women of 20–60 years of age based on polyp, adenomyosis, leiomyoma, malignancy, coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, and not-yet-classified (PALM COEIN). Materials and Methods: It was a hospital-based prospective study among 136 patients with AUB aged 20–60 years. History, general and gynecological examination, and routine gynecological examination were done using speculum examination of the vagina and the cervix and a bimanual examination. Routine investigations and an ultrasonography were done. Some were subjected to PAP smear as a routine procedure. Results: Women aged 31–50 years and multiparous were most affected with AUB in 84.6% and 88.9% of cases, respectively. According to the International Federation of Gynecology and Obstetrics type classification, the most common type of presentation was heavy menstrual bleeding in 54% of cases. The most common presenting symptom was pain in the abdomen in 4.4%. The most common-related symptom was spasmodic dysmenorrhea in 36%. The most common clinical sign was pallor in 25%. The most common associated comorbidity was anemia in 49%. Leiomyoma was the most common ultrasound diagnosis of underlying pathology in 52.2%. The most common cause of AUB as per PALM COEIN was AUB leiomyoma in 52.2%. Conclusion: Our study shows that the causation of AUB was multifactorial (though in some cases, solitary lesions were found) involving the entire female reproductive system resulting in a single common presentation as AUB.