We analyzed the usefulness of a symptom questionnaire to screen for radiation-induced brachial plexopathy (RIBP) after breast cancer treatment. Four questions addressed distal and proximal paresis: impaired hand functions, problems raising the arm, carrying weights, and lifting objects from a high shelf. Eighty-one relapse-free patients were neurologically examined. Treatment was mastectomy (51%) or breast-conserving surgery (49%), radiotherapy to the supraclavicular +/- axilla with median 60 Gy maximum dose. Sixty-five subsequent control patients had breast-conserving surgery and radiotherapy to the breast only with 55 Gy median dose. Median follow up was 10 and 7.4 years, respectively. Sixteen patients had RIBP, 7 had Radiation Therapy Oncology Group (RTOG) grade 1, 4 grade 2, 3 grade 3, and 2 grade 4 RIBP. Thirty-seven patients had fibrosis and 32 had arm edema. Four patients with RIBP had no fibrosis (n = 2) or fibrosis of the axilla only (n = 2). Specificity of the question "impaired hand functions" for RIBP was 0.66 (95% confidence interval [CI], 0.51-0.78); sensitivity was 0.80 (95% CI, 0.52-0.96). Specificity of the question "raising the arm" was 0.98 (95% CI, 0.9-0.99) and sensitivity was 0.18 (95% CI, 0.04-0.45); the rate of false-positive control patients was 3%. In multivariate analysis, "impaired hand functions" and fibrosis were independent indicators of RIBP (P <0.005). Patients with breast irradiation only stated moderate/pronounced impaired hand functions; and problems carrying weights and lifting objects from a high shelf in 38%, 58%, and 77%, not significantly different from patients with RIBP or the patients with supraclavicular radiation. RIBP is not necessarily associated with fibrosis. The aim of the questionnaire was screening of a population at risk for RIBP. In this group, the question "problems raising the arm" detected severe RIBP with high specificity. Negation of "impaired hand functions" excludes RIBP. Both questions should be included in follow-up questionnaires.