Laboratories with a quality system accredited to ISO/IEC 17025 have a definite advantage, compared to non-accredited laboratories, when preparing their facilities, for the Organization for Economic Cooperation and Development good laboratory practice (OECD GLP) recognition. Accredited laboratories have an established quality system covering the administrative and technical issues specified in the standard. These issues include: internal audits, job descriptions and responsibilities, procedures for equipment/instrument maintenance and calibration, document control, handling of reagents, chemicals and reference materials, sample reception and sampling, validation of test methods, traceability and uncertainty of the test results, training of personnel, client complaints, corrective and preventive actions. Several of these issues are also required for OECD GLP recognition either with a different emphasis and/or with additional requirements. This article describes the complimentary and additional issues of ISO/IEC 17025 and the OECD GLP series of principles.