One of the possibilities of treating patients with liver tumors, whether malignant or benign, is a surgical procedure. It represents today's fastest, and the most accurate treatment options, and very often it provides one of the best prognostic outcomes for the patient. Considering a fact that this work deals principally with issues related to primary tumors of a certain size and pathological condition, surgical treatment is restricted to resection - partial organ extraction. Meanwhile, in order to reach the phase of surgical treatment of the patient, it is necessary to fully study the liver anatomy and topography, its modes functioning, with special reference to its exogenous and endogenous metabolic and biochemical processes, as well as pathology that may be present in the substrate and reduce the performance of resection. It is necessary to examine the function of the entire organism, to verify whether the patient has other diseases that may be relevant to the outcome of the surgery, and to verify whether it is possible to combine surgical techniques with other treatment methods. The liver's ability of regeneration should not be neglected, since it represents one of the key, characteristics and superior features specific to this organ. The regeneration is invaluable in relation to the removal of the tumor, if the underlying pathology is not so advanced that regeneration is disabled. In summary, the liver is one of the most complex organs in the human body which requires a multidisciplinary approach, starting with a working diagnosis and proceeding with diagnostics treatment, and, hopefully, care. In this paper, patients with liver resection due to malignant diseases are compared taking into consideration various parameters: different tumors, individual features, depending on age, size, existing disease of the liver or other organs, pathohistological analysis and progression of the tumor mass, length of hospital treatment, and complications intra- and postoperatively. A particularly interesting part of the work was comparing the sizes of the growths obtained by diagnostic procedures and surgical resections to the definitely determined sizes of the pathohistological material. The data were collected at the University Hospital Center Zagreb in the time period from January 1, 2012 to December 31, 2016. Benign masses have a higher survival rate, and predominantly result in complete cure and regeneration without any further need for interventions. They are mainly associated with younger age, female sex, and hemangiomas. Data on resection performance, collected over a corresponding period to that for malignant lesions referred to above, were compared with the above mentioned parameters - size, intervention rate, diagnosis, aminotransferase, laboratory parameters, intra and postoperative course, complications, singularly for each benign formation and among each other.