THE IDENTIFICATION OF THE GENETICALLY CONTROLLED CONSTITUENTS PRESENT IN HUMAN BLOOD, TOGETHER WITH A KNOWLEDGE OF THEIR FREQUENCY OF OCCURRENCE WITHIN THE POPULATION, CAN BE USED TO ESTABLISH THE INDIVIDUALITY OF A BLOOD SPECIMEN. THE FREQUENCY-OF-OCCURRENCE INFORMATION NECESSARY FOR THIS APPLICATION REQUIRES A BLOOD DATA BASE LARGE ENOUGH TO CONSTITUTE A STATISTICALLY VALID SAMPLE OF THE POPULATION. A PROTOTYPE FOR A COMPUTERIZED NATIONAL BLOOD DATA SYSTEM HAS BEEN DESIGNED FOR THE PURPOSES OF STORING AVAILABLE BLOOD DATA AND DEVELOPING THE REQUIRED STATISTICAL INFORMATION. (AUTHOR ABSTRACT)