Tumour staging of colonic cancer has become increasingly important due to advancements in minimally invasive surgical techniques and potential benefits of neoadjuvant treatments for advanced but operable tumours. Selection of patients for the latter is based on CT-scans although the staging quality of this image modality is widely debated. Endoscopic ultrasonography (EUS) has not routinely been used for staging colonic cancer. This article presents the current knowledge of EUS for T-staging of colonic cancers and discusses the rationale for its supplement to routine CT-scans in selected patients.