We tested an automated system which imported computer-generated clinical data on a patient s anticoagulant medication and produced conversational voice mail messages that were dialled out automatically to patients at home. During the first 18 months of use, more than 30,000 reports were delivered by telephone. The client population was 1755 patients, 51% of whom were aged over 70 years. The telephone system was used by 1419 of the patients (81%) and 336 (19%) were classified as non-users. The most common reasons for non-use were: inability to use the telephone (6.8%), not having a tone-dial telephone (required to access the automated system) (5.2%) and hearing impairment (3.6%). An opinion survey confirmed a high degree of user satisfaction with the service. Eighty-five per cent of patients using the telephone system received their result by 19:30-in time to influence the same day's dose. We made operational savings of pound 5000 per annum in comparison with the postal method of delivering results. The system successfully helped our laboratory to deliver large quantities of computed data rapidly and safely to a vulnerable patient population in an acceptable way.