The 21-gene recurrence score (RS) is a gene expression profile assay currently endorsed for use in patients with endocrine-sensitive node-negative breast cancers. The RS has been shown to augment current 'prognostic' and 'predictive' assessments of relapse risk and chemotherapy benefits, respectively, and lead to significant change in oncologists' recommendations for adjuvant chemotherapy, with an overall reduction in chemotherapy utilization. The RS (Oncotype DX) is marketed by Genomic Health Inc. (CA, USA) and currently retails for approximately US$4290 per patient. Like all novel tests/therapies, however, these upfront costs should be examined in the context of all its clinical benefits through cost-effectiveness or cost-utility evaluations. This review highlights the clinical evidence supporting RS testing for patients with endocrine-sensitive node-negative breast cancers, and examines all published economic evaluations that examined its 'value for money' in this setting.