Brain tumor, just like any other tumor, represents a pathologic formation that originated as a consequence of excessive multiplication of abnormal cells. The growth of the neoplasm exceeds the growth of normal tissue, it is biologically nonpurposive, irregular and disorganized, and does not stop by eradicating the cause of this change. Tumors are classified as primary or secondary. Primary tumors are those tumors that originated from the brain parenchyma, and the secondary tumors are metastases, in which malignant cells reach the brain through blood. There can also be inherent tumors found in the brain, such as dermoids and epidermoids. Primary tumors are classified as benign or malignant. Problem with benign tumors is their creation and growth, because they exert pressure on surrounding structures with their volume. The other problem is their placement. If the benign tumor is located in the depth of brain parenchyma or is in contact with vital structures, then this becomes an obstacle for proper treatment. Malignant tumors are more serious and often life-threatening due to their fast growth and invasion in surrounding structures. Tasks of a nurse-anaesthesiology technician as a member of the operating team in brain tumor surgery are:  - Preparation of patient and surroundings  - Preparation of anaesthetic machine  - Preparation of intubation equipment and materials  - Preparation of everything needed for installing a central venous catheter  - Preparation of everything needed for installing a catheter for invasive heart pressure measurement  - Preparation and installation of a machine that measures TOF muscle relaxations  - Preparation and installation of a BIS electrode for measuring state of consciousness  - Preparation and installation of perfusor for anaesthetics  - Preparation of drugs and other things necessary for a scalp block