Summary: Purpose: We tested whether the behavioral components of an Intracarotid Amobarbital Protocol (IAP) had criterion validity. It was hypothesized that a recognition-memory test designed for intracarotid injections and used to predict the risk of global amnesia before an elective temporal lobectomy should also identify persons who are severely amnesic due to other neurologic causes. Divergent validity predicts that speech tasks would be unaffected by amnesia. Test-retest reliability also was measured.Methods: Fifteen persons with severe amnesia were administered four alternate forms of a yesho recognition-memory protocol and a speech protocol. No drug injection occurred. Standardized neuropsychological tests were used to divide the amnesic group into those with Global Amnesia (i.e., retain no ongoing memories), Severe Amnesia (i.e., memory impaired), and Amnesia Plus (severe amnesia plus other neuropsychologic deficits).Results: Two persons with Global Amnesia obtained scores at or below chance (i.e., failed) on the memory protocol. Unexpectedly, 12 of 13 severely amnesic persons obtained nearperfect memory scores. Amnesia had no impact on the speech protocol. PassFail outcomes were highly correlated across all four sets.Conclusions: A four-item IAP memory protocol showed good reliability and criterion validity in identifying the rare condition of Global Amnesia, but it was insensitive to other disabling, severe amnesic disorders. This IAP memory protocol might have validity in predicting a postsurgical Global Amnesic disorder, but it did not identify and therefore could not predict other more common severe amnesic disorders. Key Words: IAP-Memory-Validity.The Wada test or intracarotid amobarbital protocol (IAP) has been used clinically for almost 40 years to measure cerebral lateralization of speech (l), and predict severe amnesic syndromes (2-4). More recently clinicians use IAP results to confirm lateralization of a temporal lobe seizure focus ( 5 ) and predict verbal memory loss (6,7). For a more thorough review of how this procedure has evolved, see Rausch and Langfitt (7), Acharya and Dinner (S), and a special issue of Bruin and Cognition (9,lO). The purpose of this article is to review empirically based evidence that IAP memory protocols can reliably and validly measure very severe memory disorders, including global amnesia.Base rates of global amnesia after temporal lobectomy