Postoperative wound-site bleeding, tissue inflammation and seroma formation are well-known complications in the field of breast surgery. Hemostatic agents consisting of polysaccharides may be used intra-operatively to minimise postoperative complications. We conducted a prospective randomised-controlled, single-centre study including 136 patients undergoing breast-conserving surgery for invasive or intraductal breast cancer. Of these, 68 patients were randomised to receive an absorbable polysaccharide hemostatic agent into the wound site during surgery, while 68 patients were randomised to the control group and did not receive any hemostatic agent. Primary outcome was the total volume of postoperative drained fluid from the surgical site. Secondary outcomes were the number of days until drain removal and rate of immediate postoperative surgical site infection Patients in the intervention group had significantly higher drainage output volumes compared with the control group 85 mL (IQR 46.25-110) versus 50 mL (IQR 30-75), respectively; (P = .003). Univariable linear regression analyses showed a significant association between the surgical specimen and the primary outcome (P < .001). After multivariable analysis, the use of absorbable polysaccharide hemostatic product was no longer significantly associated with a higher drainage output and only the size of the surgical specimen remained a significant predictor. The number of days until drainage removal and the postoperative seroma formation were higher in the intervention group (P = .004) and (P = .003), respectively. In our study, intraoperative application of polysaccharide hemostatic agent during breast-conserving surgery did not decrease postoperative fluid production. Only the size of the surgical specimen was significantly associated with postoperative drainage volume.