Breast reconstruction (BR) is undertaken to improve cosmetic outcomes, but how this is optimally assessed is uncertain. This review summarises current methods for assessing cosmesis after reconstructive surgery and makes recommendations for future practice. A comprehensive systematic review identified all studies with 20 or more participants that evaluated the cosmetic outcome of BR. Four evaluation criteria (reporting of study inclusion criteria, type and timing of BR and timing of assessment) were used to assess study quality. Articles reporting at least three of the four criteria were considered robust and further summarised to report methods of cosmetic assessment, assessor details and the scoring systems used. 122 primary papers assessed cosmesis in 11,308 women with median follow-up of 28.8 months (range 18.0-42.9 months). Cosmesis was assessed by either healthcare professionals or patients in 33 (27.1%) and 37 studies (30.3%), respectively, and by both professionals and patients in 52 (42.6%). Professional assessments included 43 (40.2%) clinical, 49 (45.8%) photographic and 13 (12.1%) geometric assessments conducted by between 1 and 26 observers. Surgeons were most frequently involved in assessments (n = 71, 67.6%), but in 38 (36.1%) papers the assessor's profession was not reported. Twenty-seven (25.7%) papers used previously published assessment scale. Patients' views were assessed in 89 studies, using questionnaires (n = 63) or interviews (n = 12); 14 (15.7%) did not report how patients' views were obtained. Current methods for assessing the cosmetic outcome of BR vary widely. A valid patient-centred assessment method is required to fully understand the outcomes of BR and to inform decision-making.