Doctor Walter Dandy was a pioneer in the surgical treatment of trigeminal neuralgia. The Frazier-Spiller operation had been the standard operation for trigeminal neuralgia. Doctor Dandy pioneered the approach through the posterior fossa. He sectioned the lower-most 30 percent of the trigeminal nerve and found that trigeminal neuralgia was relieved. Anesthesia dolorosa did not develop, and the patients had only minimal sensory loss. Dandy's operation was not widely accepted, but microvascular decompression as described by Jannetta was developed by application of Dandy's principles. In twenty patients, we performed a partial trigeminal rhizotomy using Dandy's technique. A small sub-occipital craniectomy was performed and the trigeminal root entry zone exposed. The lowermost 30 percent of the trigeminal nerve was elevated with a blunt hook. The coagulating cautery was applied to the hook and the nerve partially sectioned. In each case, the trigeminal neuralgia was completely relieved. Each patient developed a minimal sensory loss in the second division of the trigeminal nerve. The corneal reflex was preserved in all cases. No patient has developed anesthesia dolorosa. Partial trigeminal rhizotomy is an alternative to microvascular decompression. The operation is technically easy to perform and should resume its rightful place in the neurosurgical treatment of trigeminal neuralgia.