Advances in the diagnosis and management of congenital heart disease have led to a marked improvement in the survival of adult with congenital heart disease (ACHD) patients. However, ACHD patients are a heterogeneous population, with a large spectrum of anatomic substrates even within specific lesions. In addition, the nature of previous surgery and other intervention is highly variable rendering each patient unique and residual anatomic and haemodynamic abnormalities are very common. As the ACHD population continues to age, acquired heart disease will also require cardiac imaging assessment. It is increasingly recognized in ACHD community that the diagnostic utility of a multimodality cardiovascular approach is greater than the sum of individual tests. In ACHD patients, diagnostic information can be obtained using a variety of diagnostic tools. The aims of this document are to describe the role of each diagnostic modality in the care of ACHD patients and to provide guidelines for a multimodality approach. The goal should be to provide the most appropriate and cost-effective diagnostic pathway for each individual ACHD patient.