The paper considers surgical treatment of patients with partially thrombotic giant and fusiform aneurysms of the posterior cerebral arteries (PCA), which is a challenge of cerebrovascular neurosurgery. Giant, fusiform aneurysms are clinically manifested themselves as a mass effect in 80% of cases and as spontaneous subarachnoidal hemorrhage in 20%. Due to their vicinity of the brain stem, giant aneurysms of PCA in any clinical course present a real threat to a patient's life. A case of clipping of partially thrombotic giant aneurysm of PCA by means of tunnel clips to form the wall of a vessel from an apron cut from the aneurysmal wall is considered in detail. Surgical treatment of partially thrombotic giant and fusiform aneurysms is identified as an individual problem of cerebrovascular neurosurgery, which awaits a sophisticated study in order to define an adequate surgical treatment.