Over 100 giant colonic diverticuli have been recorded in the literature to date. The magnetic resonance imaging (MRI) and pathophysiology of their aetiology have rarely been described.To report a giant colonic diverticulum along with the MRI of this clinical entity.An 87 year old female presented with symptoms of tenesmus, urgency and alteration in bowel habit. A type I giant colonic diverticulum was diagnosed and a segmental colonic surgical resection was performed. The plain abdominal radiograph, barium enema and MRI, along with classification and management options are presented.Giant colonic diverticuli are rare surgical curiosities that may be successfully treated with either primary segmental or extended colonic resection.