Twenty-nine patients, who each received modified radical mastectomy, were recruited for this study. Wounds were inspected daily for the presence of flap necrosis, infection, and seroma. Drain fluid (20 ml) was collected at 6 a.m. on postoperative days 1, 2, and 5 and the levels of interleukin (IL)-4, IL-6, tumor necrosis factor-alpha, and interferon-gamma determined. For patients with no wound events, only IL-6 levels were elevated during the initial phase, but in the later phase the IL-6 levels dropped with a corresponding rise in tumor necrosis factor-alpha levels. In patients with flap necrosis, there was a sequential rise of IL-4 on day 1, IL-6 on day 2, and tumor necrosis factor-alpha on day 5, but only IL-4 was found to be a statistically significant factor associated with necrosis. In patients with seroma, the levels of IL-4 and interferon-gamma were persistently low and were both statistically significant. To conclude, IL-6 and tumor necrosis factor-alpha are important in normal postoperative wound healing and IL-4 and interferon-gamma may be associated with postoperative necrosis and seroma.