This publication by the World Health Organization (WHO) details the assessment process for listing Performance Evaluation Laboratories (PELs) for in vitro diagnostics (IVD). It serves as a guide for candidate laboratories seeking to become designated PELs under WHO's evaluation framework. The document outlines the standardized assessment procedure to ensure the safety, quality, and performance of IVDs, particularly in resource-limited settings. The assessment involves a comprehensive review of product dossiers, performance evaluations, manufacturing site inspections, and labeling reviews. The text provides guidance for WHO Member States, UN agencies, and international organizations in their procurement decisions. It includes detailed instructions on the application process, audit stages, and the criteria for PEL designation. The intended audience includes laboratory professionals, regulatory authorities, and organizations involved in IVD procurement.