A low-cost Medical Data Handling System (MDHS) has been developed on a Digital Equipment Corporation PDP 11V03 computer system with dual floppy discs using BASIC in a time-shared configuration. The MDHS can be called up by one or more users to collect, update, or store patient data on floppy discs. Various analysis options are available to generate reports for patient management or administrative purposes. All software is written in BASIC to facilitate changes or expansion, and to reduce the costs in transferring the software system to other low-cost microprocessor systems currently available. The MDHS can be used in a variety of hospital departments for data management by simple customization of the I/O software to take advantage of the general purpose routines. The system is currently in use for generating daily patient-summary clinical-laboratory reports for ICU and CCU patients. This is the first part of a two-part article. The second part will follow in the July-September issue of this Journal.