Purpose: To give recommendations on patient selection criteria for the use of accelerated partial-breast irradiation (APBI) based on available clinical evidence complemented by expert opinion. Methods and materials: Overall, 340 articles were identified by a systematic search of the PubMed database using the keywords "partial-breast irradiation" and "APBI". This search was complemented by searches of reference lists of articles and handsearching of relevant conference abstracts and book chapters. Of these, 3 randomized and 19 prospective non-randomized studies with a minimum median follow-up time of 4 years were identified. The authors reviewed the published clinical evidence on APBI, complemented by relevant clinical and pathological studies of standard breast-conserving therapy and, through a series of personal communications, formulated the recommendations presented in this article. Results: The GEC-ESTRO Breast Cancer Working Group recommends three categories guiding patient selection for APBI: (1) a low-risk group for whom APBI outside the context of a clinical trial is an acceptable treatment option; including patients ageing at least 50 years with unicentric, unifocal, pT1-2 (≤30 mm) pN0, non-lobular invasive breast cancer without the presence of an extensive intraductal component (EIC) and lympho-vascular invasion (LVI) and with negative surgical margins of at least 2 mm, (2) a high-risk group, for whom APBI is considered contraindicated; including patients ageing ≤40 years; having positive margins, and/or multicentric or large (>30 mm) tumours, and/or EIC positive or LVI positive tumours, and/or 4 or more positive lymph nodes or unknown axillary status (pNx), and (3) an intermediate-risk group, for whom APBI is considered acceptable only in the context of prospective clinical trials. Conclusions: These recommendations will provide a clinical guidance regarding the use of APBI outside the context of a clinical trial before large-scale randomized clinical trial outcome data become available. Furthermore they should promote further clinical research focusing on controversial issues in the treatment of early-stage breast carcinoma.