Approximately 10–20% of women of reproductive age suffer from endometriosis, with 70–90% of these women reporting chronic pain symptoms that persist during their menstrual cycle. We are presenting a case in which a novel form of noninvasive brain stimulation called transcranial direct current stimulation was used as an intervention in a 32-year-old woman with persistent, chronic pain symptoms caused by endometriosis for 20 years. Ten daily, 20-min sessions of 2-mA anodal transcranial direct current stimulation were applied over the left primary motor cortex. Acutely, visual analog scale pain symptoms were reduced by 60%. There were also significant decreases in modules of the Endometriosis Health Profile. At the 4-month follow-up, the patient still expressed an overall decrease in pain symptoms of 30%.