Risk factors for chronic pain up to 9months after breast cancer surgery include younger age, psychological vulnerability, axillary clearance surgery, and severe acute postoperative pain. Chronic postsurgical pain (CPSP) is a common postoperative adverse event affecting up to half of women undergoing breast cancer surgery, yet few epidemiological studies have prospectively investigated the role of preoperative, intraoperative, and postoperative risk factors for pain onset and chronicity. We prospectively investigated preoperative sociodemographic and psychological factors, intraoperative clinical factors, and acute postoperative pain in a prospective cohort of 362 women undergoing surgery for primary breast cancer. Intraoperative nerve handling (division or preservation) of the intercostobrachial nerve was recorded. At 4 and 9months after surgery, incidence of chronic painful symptoms not present preoperatively was 68% and 63%, respectively. Univariate analysis revealed that multiple psychological factors and nerve division was associated with chronic pain at 4 and 9months. In a multivariate model, independent predictors of CPSP at 4months included younger age and acute postoperative pain (odds ratio OR 1.34, 95% confidence interval CI 1.12 to 1.60), whereas preoperative psychological robustness (OR 0.70, 95% CI 0.49 to 0.99), a composite variable comprising high dispositional optimism, high positive affect, and low emotional distress, was protective. At 9months, younger age, axillary node clearance (OR 2.97, 95% CI 1.09 to 8.06), and severity of acute postoperative pain (OR 1.17, 95% CI 1.00 to 1.37) were predictive of pain persistence. Of those with CPSP, 25% experienced moderate to severe pain and 40% were positive on Douleur Neuropathique 4 and Self-Complete Leeds Assessment of Neuropathic Symptoms and Signs pain scales. Overall, a high proportion of women report painful symptoms, altered sensations, and numbness in the upper body within the first 9months after resectional breast surgery and cancer treatment.