Thecaloscopy is less invasive exploration of spinal subarachnoid space with ultra-thin flexible endoscope and endoscopic fenestration of scars and adhesions. Thecalopscopy was used in Russian neurosurgery at the first time. Since 2009 we operated 32 patients with following diagnosis: 17 - spinal adhesive arachnoiditis (8 - local forms, 9 - diffuse forms), 12 - spinal arachnoid cysts (7 - posstraumatic cysts, 5 - idiopathic cysts), 3 - extramedullary tumors (thecaloscopic videoassistance and biopsy). In all cases we realized exploration of subarachnoid space and pathologic lesion with endoscopic perforation of cyst or dissection of adhesions using special instrumentation. Mean follow-up in our group was 11.4 months. Neurological improvement (mean 1.4 by modified Frankel scale, 1.8 by Ashworth spasticity scale) was seen in 87% of patients operated for spinal arachnopathies. Temporary neurological deterioration (mild disturbances of deep sensitivity) was seen in 9% of patients and managed successfully with conservative treatment. 1 (3.1%) patient was operated 3 times because of relapse of adhesions. There were no serious intraoperative complications (e.g., serious bleeding, dura perforation etc). Postoperative complications included 1 CSF leakage and 1 postoperative neuralgic pain. Mean term of hospitalization was 7.6 days. According to our data, we suppose that thecaloscopy is efficient and safe method, and should be widely used for spinal arachnopaties, adhesive arachnoiditis and arachnoid cysts. Taking into account that adhesive spinal arachnoiditis is systemic process and spinal arachnoid cysts can be extended as well, thecaloscopy may be regarded as the most radical and less-invasive way of surgical treatment existing currently in neurosurgery.