This publication provides guidelines for the implementation of quality assurance and control programmes concerning the combined medical diagnostic modality of positron emission tomography (PET) and computed tomography (CT). These independent, but complementary, imaging techniques are in frequent and increasing use within the fields of diagnostic imaging, oncology, cardiology and neurology, where they allow physicians to locate and diagnose malignant diseases accurately. This publication establishes guidelines for acceptance testing and routine quality control as necessary for optimal clinical performance. Specific topics of discussion include frameworks for reference values, tolerances and action levels, minimal required configurations with corresponding performance characteristics, and the management of ancillary equipment.