Background: The burden of dysmenorrhea is greater than any other gynecological complaint. The effects extend beyond individual women to society, resulting in an important loss of productivity annually. Thus, World Health Organization estimated that dysmenorrhea is the most important cause of chronic pelvic pain. Adenomyosis and endometriosis are the most frequent causes of secondary dysmenorrhea in young women. Aim: The aim of this study was to evaluate the causes of secondary dysmenorrhea by diagnostic laparoscopy and find out the prevalence of endometriosis as a cause of secondary dysmenorrhea. Methodology: A total of 35 women with persistent dysmenorrhea and negative imaging findings were subjected to diagnostic laparoscopy after proper investigations and informed consent. Results: In all 35 cases that underwent laparoscopy, 26 women had endometriosis (74.2%). There were 6 women diagnosed with PID (17.14%), one woman with adenomyosis, and two women with ovarian cysts. Among women with endometriosis, 53.8% had ovarian endometriomas, 76.9% had endometriotic lesions, and 34.6% had adhesions. Endometriosis was found maximum (42.9%) in the ovaries followed by POD (40%), uterosacral ligaments (17.1%), fallopian tubes (11.4%), bladder, and pelvic peritoneum 2.9% each. Histopathology was sent for 30 cases and only 24 cases reported back with biopsy reports. Biopsy-proven endometriosis and laparoscopically diagnosed endometriosis were analyzed and compared. The sensitivity of laparoscopy was found to be 77.78%, and the specificity 33.33%. Conclusion: Endometriosis should be suspected in women of the reproductive age group with secondary dysmenorrhea. Laparoscopy is the most reliable technique for the diagnosis of endometriosis. Laparoscopy should be combined with histopathological examination since endometriosis is likely to be overdiagnosed or underdiagnosed if only visual diagnosis is used.