Previous studies have shown that dysmenorrhea produces low-back pain and an electromyographic (EMG) pattern typical of trauma-induced low-back pain. To determine the effects of high-velocity low-amplitude osteopathic manipulative treatment (OMT) on this type oflowback pain, 12 dysmenorrheic subjects were assigned to a group receiving OMT or to a group not receiving OMT (or both). Eight subjects participated in both groups, the other four being equally distributed between groups. Osteopathic manipulative treatment significantly decreased EMG activity during extension of the lumbar spinae erector muscles and abolished the spontaneous EMG activity. These EMG changes coincided with the patient's report of alleviated low-back pain and menstrual cramping. Osteopathic manipulative treatment did not change the creatinine kinase, lactate dehydrogenase or lactate dehydrogenase isoenzyme activity, or myoglobin concentration.