Primary dysmenorrhea is painful menstrual cramps without any evident pathology to account for them, and it occurs in up to 50% of menstruating females and causes significant disruption in quality of life and absenteeism. Current understanding implicates an excessive or imbalanced amount of prostanoids and possibly eicosanoids released from the endometrium during menstruation. The uterus is induced to contract frequently and dysrhythmically, with increased basal tone and increased active pressure. Uterine hypercontractility, reduced uterine blood flow, and increased peripheral nerve hypersensitivity induce pain. Diagnosis rests on a good history with negative pelvic evaluation findings. Evidence-based data support the efficacy of cyclooxygenase inhibitors, such as ibuprofen, naproxen sodium, and ketoprofen, and estrogen-progestin oral contraceptive pills (OCPs). Cyclooxygenase inhibitors reduce the amount of menstrual prostanoids released, with concomitant reduction in uterine hypercontractility, while OCPs inhibit endometrial development and decrease menstrual prostanoids. An algorithm is provided for a simple approach to the management of primary dysmenorrhea.