Trigeminal neuralgia is often seen in elderly persons. Two hundred patients with trigeminal neuralgia were submitted to microvascular decompression by a retrosigmoid approach. The surgical procedure is described. Vascular compression of the nerves was noticed in all these patients at operation. One hundred ninety-seven had relief of symptoms postoperatively, for a 98.5% cure rate. In addition, we suggest that another important cause is arteriosclerosis.