Greater amount and duration of postoperative wound drainage after lymphadenectomy impede healing. We evaluated the influence of early vs delayed initiation of shoulder mobilization on postoperative drainage. Fifty-seven women with clinical stage I or II breast cancer were randomized to either early (postoperative day 2) or delayed (postoperative day 5) shoulder motion. Early vs delayed time of exercise initiation had no effect on total amount or duration of drainage, either as an inpatient or outpatient. The two groups were determined to be homogeneous as to age, breast size, weight, height, obesity, previous biopsy, excision of pectoralis minor, excision of thoracodorsal complex, level of axillary dissection, total number of lymph nodes, number of positive lymph nodes, lymphatic vessel invasion (with negative lymph nodes), and whether the dominant hand was on the side operated on. The two factors predicting greater drainage were large numbers of positive lymph nodes and no previous surgical biopsy (as in one-step procedure).