Doses of factor VIII to be infused into a haemophiliac undergoing major surgery were
            calculated on a micro-computer. The degree to which the particular patient responded
            to infused factor VIII and the rate at which it decayed were estimated by two pre-operative
            experiments. Plasma levels of factor VIII were predicted over fourteen days during
            which time the patient was infused with 53,000 iu. A continuous plot of predicted
            values with time was displayed on a video monitor. The predicted values showed good
            agreement with assay results.
         Key words
Haemophilia - Factor VIII - Computer - Surgery