Clinical records and patient interviews in 37 cases of trigeminal neuralgia treated by microvascular decompression by a single surgeon were studied retrospectively. Outcomes were determined with an average follow-up period of 43 months. Abnormalities in the region of the trigeminal nerve were identified in each case. Patients undergoing microvascular decompression as a primary procedure were cured (total pain relief without further therapy) at a rate of 91%, versus 43% in patients treated with destructive procedures (rhizotomies) prior to microvascular decompression (p less than 0.005). Analysis also suggests that trigeminal neuralgia of greater than 9 years' duration was cured at a rate of only 42%, versus 88% in cases of less lengthy duration (p less than 0.005). Sex and age at time of surgery were not significant predictors of outcome. There were no deaths in this group of patients aged from 32 to 90 years. A horizontal surgical approach is described.