A 41-year-old breast cancer patient received a course of acupuncture for intense pain following a subcutaneous mastectomy and a latissimus dorsi flap reconstruction. She was treated with acupuncture using paravertebral segmental points, trigger points, plus contralateral L14 on the non-lymphoedematous arm. She experienced an episode of galactorrhoea 6 days following the first treatment and during the second treatment. She had not lactated for 4 years. Computed tomography and magnetic resonance imaging of the brain revealed no focal abnormality. In the traditional Chinese literature, acupuncture has been used to promote lactation using the ‘Tianzong’ acupoint SI11. This acupoint coincided with a trigger point over infraspinatus that was included in the acupuncture treatment. Quantitative analysis has shown an increase in the production of prolactin and oxytocin following acupuncture. These hormones are involved in the synthesis and release of milk from mammary glands, respectively.