This document provides guidance on the interpretation of GMP principles for human and veterinary medicinal products according to Directives 2003/94/EC and 91/412/EEC. It describes the qualification and validation of facilities, equipment, utilities, and processes in drug manufacturing, and it can optionally be applied to active substances without imposing additional requirements. Manufacturers must control critical aspects throughout the entire product and process lifecycle through qualification and validation. Changes that affect product quality should be documented, and their impact on the validation status should be assessed. Computerized systems must be validated in accordance with Annex 11, taking into consideration the guidelines ICH Q8, Q9, Q10, and Q11.