Accessory fissures that separate aberrant lung lobes are not only interesting anatomical observations, but also have a definiteimportance as they may cause diagnostic confusion in radiological and pathological evaluations. In the case reportedhere, a rare type of separation of the left lung by an unusual fissure is described. The left lung of a 67-year-old Caucasianfemale cadaver showed an accessory fissure that crossed the mediastinal, apical and anterior costal surfaces. The aberrantfissure separated the organ into a small upper-medial anterior lung lobe (lobus minimus) and a much larger aberrant lobe(lobus magnus). At the pulmonary hilum, the artery, vein and bronchus of the small aberrant lobe were clearly identifiable.During analysis of radiological images such as X-ray and computed tomography, the existence of such aberrant fissures andlobes have to be known in detail in order to separate between simple anatomic variation of the lungs and a number of lungpathologies including scar, pulmonary bulla, atelectasis or even mediastinal mass.