Gamma knife is approximately 18-ton machine that use gamma emitter cobalt-60 as a source. Over time, gamma knife was technically perfected and in early 80’s in clinical use enters the model with 201 photon beam arranged in a hemispheric ring which allows getting more isocentric distribution of absorbed dose that is characteristic of high geometric adjustment of dose distribution and high tumor dose gradient. It represents a breakthrough in the medical field and sets the basis for the development of stereotactic radiosurgery. This is a method of physical guidance beams of ionizing radiation by using a metal stereotactic frame, in order to cure small, pathological processes within the skull. Gamma knife has been successfully used for various intracranial indications such as pituitary tumors (benign and malignant), meningiomas, treatment of arteriovenous malformations (AVM) and trigeminal neuralgia. Radiosurgical principles of what we know from the last century, are now extended to extracranial indications such as lung, spinal cord and liver tumors. Its noninvasiveness, excellent results in controlling tumor growth and healing with a reduced patient’s number of days of hospitalization over other therapeutic modalities, gives the gamma knife advantage and increasing rate of usage in the clinical practice.