THE SCIENTIFIC INTERROGATION UNIT OF THE ISRAEL POLICE BEGAN USING HYPNOTIC TECHNIQUES IN 1973 AFTER IT CONCLUDED THAT MUCH RELEVANT INFORMATION PERCEIVED AT CRIME SCENES WAS LATER FORGOTTEN, AND THAT EYE WITNESSES AND COMPLAINTANTS WERE UNABLE TO REPORT CRUCIAL FACTS AND DETAILS. THIS FORGOTTEN MATERIAL MAY INCLUDE DESCRIPTIONS OF SUSPECTS, VEHICLES, LICENSE NUMBERS, AND WEAPONS. CRIMINAL INVESTIGATIONS IN WHICH HYPNOSIS HAS BEEN USED CAN BE DIVIDED INTO THREE MAJOR CATEGORIES: (1) CASES IN WHICH IT WAS ASSUMED THAT THE LOSS OF MEMORY WAS DUE TO A MOTIVATED REPRESSION OF DETAILS AND/OR EVENTS EVOKING OVERWHELMING ANXIETY; (2) CASES IN WHICH HYPNOSIS WAS USED IN ORDER TO RECALL FORGOTTEN DETAILS OR EVENTS THAT AT THE TIME OF THE CRIME SEEMED ORDINARY OR INSIGNIFICANT, BUT WHEN THE CRIME WAS REPORTED AT A LATER DATE, BECAME CRUCIAL AND EVOKED DIFFERENT LEVELS OF ANXIETY; AND (3) CASES IN WHICH HYPNOSIS WAS USED WHEN THE SUBJECT SEEMED TO GIVE THE INFORMATION NEEDED BY INVESTIGATORS, BUT INFORMATION THAT NONETHELESS DID NOT FIT IN WITH OTHER EVIDENCE IN A PARTICULAR CASE. IN ALL, HYPNOSIS HAS BEEN USED IN ORDER TO IMPROVE THE MEMORY OF 40 SUBJECTS. THE EVALUATION OF THE EXPERIENCE IN THESE CASES INDICATES THAT HYPNOSIS MAY BE A POTENTIAL TOOL TO ELICIT ESSENTIAL INFORMATION FROM COOPERATIVE SUBJECTS. IT WAS FOUND THAT THE AMOUNT OF INFORMATION OBTAINED THROUGH HYPNOSIS INCREASED WITH THE MEANINGFULNESS OF THE MATERIAL TO BE RECALLED AND THE LEVEL OF ANXIETY INVOLVED. FOUR CASE STUDIES ARE BRIEFLY REVIEWED. IT IS SUGGESTED THAT HYPNOSIS SHOULD BE EMPLOYED ONLY UNDER THE FOLLOWING CONDITIONS: (1) WHEN WITNESSES OR VICTIMS EXPRESS THEIR FULL WILLINGNESS TO COOPERATE; (2) AFTER PRECLINICAL EVALUATION OF THE SUBJECT'S PSYCHOLOGICAL WELFARE; (3) WHEN A TRAINED PSYCHIATRIST OR PSYCHOLOGIST WITH ADDITIONAL SPECIALIZED TRAINING IN HYPNOTIC TECHNIQUES IS AVAILABLE TO PERFORM THE PROCEDURE; AND (4) ONLY IN THE PRESENCE OF UNBIASED OPERATORS WHO WILL CONCENTRATE THEIR EFFORTS ON USING THE HYPNOSIS TO HELP THE SUBJECT RECALL THAT INFORMATION WHICH COINCIDES WITH THE PREDETERMINED GOAL OF THE INTERVIEW. IT IS CONCLUDED THAT HYPNOSIS IS A USEFUL AND EFFECTIVE TOOL FOR SCIENTIFIC INTERROGATION IN CRIMINAL INVESTIGATIONS, AND IT IS RECOMMENDED THAT APPLIED RESEARCH IN ACTUAL INVESTIGATIONS AND METHODOLOGICAL RESEARCH BE SIMULTANEOUSLY UNDERTAKEN. REFERENCES ARE PROVIDED. (KBL)