IN ONE STRATEGY for the treatment of unilateral vestibular schwannomas measuring up to 3 cm in diameter, decision analysis shows that gamma knife radiosurgery has probabilistic dominance over microsurgical resection. That is, radiosurgery produces better results for any value assigned to treatment outcomes (ranked from best to worst) of the following: no complications, hearing loss only, residual/recurrent tumor, facial paralysis, major disability, or death. This little-known principle of decision analysis will be explained. It implies that when patients prefer the preservation of facial nerve function, even if that requires leaving a tumor remnant, then gamma knife radiosurgery is a better treatment strategy than microsurgical resection.