Employing an electronic digital computer with magnetic tapes, the complete clinical records of 361 patients were placed on magnetic tape for storage and retrieval. Mimeograph-reproduced marksense cards served to transfer data to the tape. Searching, correlating, and testing of medical data was done very rapidly and without limitation as to the number of relationships and conditions. Records were compact and quickly transposed on retrieval, which was not the case with the previous punch-card techniques. This pilot study indicates that the flexibility of the mark-sense form and the use of magnetic tape provide a workable method of clinical record storage, retrieval, processing, and analysis.