OBJECTIVE: To identify factors associated with the risk of developing dysmenorrhea or the severity of dysmenorrhea in women with surgically confirmed ovarian endometriomas. STUDY DESIGN: 710 patients with surgically diagnosed ovarian endometriomas were interviewed and their charts read. Fourteen factors were considered. Among the 710 patients, 376 patients had major complaint of dysmenorrhea and were evaluated to identify factors associated with the severity of dysmenorrhea. RESULTS: The logistic regression model identified younger age at surgery, previous medication use, presence of adhesion, and presence of adenomyosis as risk factors for dysmenorrhea. For the severity of dysmenorrhea, the presence of adenomyosis was consistently and robustly identified by several statistical models with rather different assumptions as the factor associated with severity. The rAFS stage was also associated with the severity, but the association may be explained by the presence of adenomyosis. CONCLUSION: The presence of adenomyosis has been consistently identified as a risk factor for both dysmenorrhea and its severity. Younger age at surgery, presence of adhesion, and previous use of endometriosis-related medication are additional risk factors for dysmenorrhea. For the severity of dysmenorrhea, there are other factors than the presence of adenomyosis that may influence the severity of dysmenorrhea. Copyright 2008 S. Karger AG, Basel.