A microcomputer database system for the storage, retrieval, and statistical analysis of data associated with the treatment of haemophilia and other defects of haemostasis is described. The hardware requirements are an IBM compatible PC with both hard and floppy disc drives and a suitable printer. The system was written using Smartware II, a powerful integrated software package which incorporates database, word processor, spreadsheet and communications functions. The programs were written with flexibility in mind and can be readily adapted to accommodate the work patterns of any haemophilia centre. This system has now been operational in the Regional Haemophilia Centre at the Manchester Royal Infirmary since January 1990. Its introduction has led to a marked improvement in the efficiency of patient data handling with significant savings in staff time.