Clinical and Laboratory Standards Institute document I/LA33-A--Validation of Automated Systems for Immunohematological Testing Before Implementation; Approved Guideline provides guidance to the user and laboratory for validating an automated system for immunohematological testing. Current automated system methodologies are discussed. This document addresses the development of a validation plan and the information required for its creation. It includes guidelines for elements and tasks of the validation process, including installation qualification, operational qualification, and performance qualification. For each of these qualifications, the purpose, prerequisites, responsibilities, considerations for and examples of test cases, and activities performed are included. The Appendix contains templates that may be used by the laboratory for development of test cases related to and for different aspects of installation qualification, operational qualification, and performance qualification.