Accurate anatomical knowledge is necessary for liver surgery. Much of the knowledge about the left portion of the liver in the anatomy, surgery and internet texts must be improved and enriched; we propose to do this with this work. We studied 286 human livers that allowed us to determine further knowledge, along with the following information: 1) The left liver portion was larger than the right liver in 21 % of cases. 2) The left portion of the liver was formed by the first four portal segments (79 %) or by the first five (21 %). 3) The umbilical fissure tilted 50 degrees to the left relative to the sagittal plane of the liver and did not contain the left hepatic vein in 100 % of cases. 4) The left hepatic vein had an intrasegmental path and presented three drainage modalities. 5) Arterial irrigation of the left segments I and IV were born from the right branch in 16 % and from both branches in 24 %. 6) Bile drainage of right segments VI-VII reached the left hepatic canal in 21 % of cases. These results were different from the knowledge contained in the human anatomy texts used in medical schools at the general level.