The main objective of this guideline is to provide harmonised principles of genomic sampling and management of genomic data in clinical studies. This guideline will facilitate the implementation of genomic studies by enabling a common understanding of critical parameters for the unbiased collection, storage and optimal use of genomic samples and data. Further objectives of this guideline are to increase awareness and provide considerations regarding subject privacy, data protection, informed consent and transparency of findings. This guideline is intended to foster interactions amongst stakeholders, including drug developers, investigators and regulators, and to encourage genomic research within clinical studies.