A data processing system designed to improve the management and usage of blood and blood products has been developed as a pilot for general application throughout the West Midlands Regional Health Authority. The package provides for the routine clerical, patient record, and stock management aspects of a hospital blood bank laboratory. It can be tailored to the individual requirements of different laboratories and may be implemented in a variety of ways on a family of computer systems of differing power and capacity, thus accommodating widely varying workloads and archiving requirements. Bar code readers are included in the system design, and may be used for data input where standard Codabar labels are affixed to blood products by blood transfusion centres. The system has been installed in one hospital laboratory and preliminary results indicate a high degree of acceptability at all levels. Further refinement of the software to meet minor deficiencies and the requirements of the recent DHSS Health Circular BLD/2/13 are currently being specified.