BACKGROUND Plugged ducts are a common, painful condition in lactating women, but no standard treatment is currently available. OBJECTIVE This study aimed to evaluate the clinical efficacy of a newly established 6-step recanalization manual therapy (SSRMT) for treating plugged ducts. METHODS This observational study included 3497 lactating women with plugged ducts. The SSRMT comprised the following well-defined steps: (1) preparation, (2) clearing the plugged duct outlets, (3) nipple manipulation, (4) pushing and pressing the areola, (5) pushing and kneading the breast, and (6) checking for residual milk stasis. The response to the treatment was graded as I (complete resolution), II (marked improvement), III (improvement), or IV (no response). RESULTS Of the 3497 patients, the mean age was 26.7 years and 3284 (93.9%) patients were primiparas. Fever was present in 1231 (35.2%) patients. After a single SSRMT treatment, 3189 (91.2%), 173 (4.9%), and 83 (2.4%) patients achieved grade I, II, and III responses, respectively, with only 52 (1.5%) showing unresponsiveness. For the 308 (8.8% of total) non-grade I patients, a second SSRMT given 3 days later resulted in grade I, II, and III responses in 267 (7.6% of total), 28 (0.8% of total), and 13 (0.4% of total) patients, respectively, and none were absolutely unresponsive. No complications with clinical significance were observed. CONCLUSION Based on this large-scale clinical observation, SSRMT appears to be a useful, safe, low-cost treatment for postpartum plugged milk ducts.