Reporting of the outcome of radiotherapy is not satisfactory without a description of the treatment-related side effects. The purposes of this paper were: (1) to evaluate the frequency and the severity of collateral skin reactions in a group of breast cancer patients; (2) to report the acute reactions using some current scoring systems and to compare the application of them, and (3) to investigate the variation between intra- and interobservers using these different scales. We studied 108 breast cancer patients who, after surgical treatment, received adjuvant radiotherapy. Clinical skin evaluation was always performed by the same radiotherapist the last day of treatment, and the collateral radiation effects were photographed at that moment to facilitate later evaluations by another two expert doctors. Normal tissue damage was scored according to the Radiation Therapy Oncology Group/The European Organisation for Research, and Treatment of Cancer/ (RTOG/EORTC), the Danish, the European, and the Biomed2 side-effect scales. The most frequent acute complications found were erythema (91.7%), dry desquamation (29.6%) and moist desquamation (35.2%). The reactions were classified as severe in 13.9, 23, 18.5 and 13% of the patients with each of the different systems used, respectively. The concordance between the scoring of radiation-induced side effects on the skin assessed by direct observation of the patients or by examination of the photographic document was sufficient. This is a warrant of accuracy in the evaluation of acute normal tissue lesions. Our results allow us to state the advantage of the RTOG system over the others in terms of evaluating the acute effects produced by radiotherapy of women with breast cancer.