Tissue microarray analysis (TMA) allows multiple analyses on multiple patients on sections from a single paraffin block. Although it is widely used in research and in quality assurance settings, there are few references to its use in clinical practice. This study evaluated TMA assessment of breast biomarkers using immunohistochemical analysis in a clinical histopathology laboratory. Performance parameters, interobserver variability, and concordance between TMA and whole section results were assessed. The arrays had few lost or noninformative cores. A loss of stain intensity occurred in the arrays compared with the whole sections with some but not all antibodies, highlighting the need to validate the staining protocol for each antibody used on TMA sections. With recommended guidelines for specimen selection and reporting, TMA was found to be an economical replacement for whole section analysis for breast biomarkers.