From 10/1989 to 12/1992, 135 patients were treated, in Lyon, by Stereotactic Radiosurgery (RS) +/- External beam Radiotherapy (EBRT). Indications were AVMs or tumours that could not be cured by embolisation or/and surgery and are not larger than 30 to 35 mm. Lesions received 15 to 20 Gy (70% isodose) in one course. Among the 42 AVMs, only one rebled 6 months after RS and 9/15 had clinical improvement. Thirty-one had a radiological follow-up of 4 to 29 months after RS. Ten were totally obliterated, seven regressed more than 80% and six had a reduction of 50 to 80% of their AVM. Three grade 3 radio necrosis occurred for a cerebral trunk AVM and two large lesions. Three of the 15 treated meningiomas progressed after RS, 2 of them were controlled by conventional surgery. Four out of nine presenting symptoms had clinical improvement and, with a radiological follow-up of 4 to 24 months, 5 were stabilised and 6 regressed. Two grade three complications occurred for large lesions. The biological and radiological results of RS were good for the 42 treated pituitary adenomas but the high visual complication rate (12/42 with 8 grade 3) was too important and we stopped RS for these tumours except for small (less than 2 cm) adenoma at some distance from the optic chiasma. The visual complications were related to the tumour volume, the distance between the adenoma and the visual tract and pre-existent visual alterations.(ABSTRACT TRUNCATED AT 250 WORDS)