Bochdalek hernias occur as a result of congenital fusion failure of the posterolateral muscular portion of the diaphragm derived from the embryonic pleuroperitoneal membrane. The vast majority of symptomatic Bochdalek hernias are diagnosed during the neonatal period. Congenital diaphragmatic hernias showing symptoms in adulthood are rare. We report the case of a 28-year-old man who presented with subacute bowel obstruction, later diagnosed to have a left-sided incarcerated Bochdalek hernia containing an ischaemic splenic flexure and the distal transverse colon. During laparotomy, he underwent primary repair of the diaphragmatic defect and an extended right hemicolectomy with ileocolic anastomosis. The patient made a good recovery and is well at three months following surgery. This case highlights the need for surgeons to be vigilant about rare types of congenital internal hernias as they may become symptomatic later in life.