Background. Axillary web syndrome (AWS) is a condition that may develop following breast cancer surgery and that presents as a palpable axillary cord of tissue. Objective. The purposes of this study were: (1) to determine the clinical characteristics of AWS related to movement, function, pain, and postoperative edema and (2) to define the incidence of and risk factors for AWS within the first 3 months following breast cancer surgery. Design. This was a prospective cohort study with a repeated-measures design. Methods. Women who underwent breast cancer surgery with sentinel node biopsy or axillary lymph node dissection (N=36) were assessed for AWS, shoulder range of motion, function, pain, and postoperative edema (using girth measurements, bioimpedance, and tissue dielectric constant) at 2, 4, and 12 weeks. Demographic characteristics were used for risk analysis. Results. Seventeen women (47.2%) developed AWS, and AWS persisted in 10 participants (27.8%) at 12 weeks. Abduction range of motion was significantly lower in the AWS group compared with the non-AWS group at 2 and 4 weeks. There were no differences between groups in measurements of function, pain, or edema at any time point. Trunk edema measured by dielectric constant was present in both groups, with an incidence of 55%. Multivariate analysis determined lower body mass index as being significantly associated with AWS (odds ratio=0.86; 95% confidence inter-val=0.74, 1.00). Limitations. Limitations included a short follow-up time and a small sample size. Conclusion. Axillary web syndrome is prevalent following breast/axilla surgery for early-stage breast cancer and may persist beyond 12 weeks. The early consequences include movement restriction, but the long-term effects of persistent AWS cords are yet unknown. Low body mass index is considered a risk factor for AWS.