Ninety three cardiac catheterisations were carried out at St Thomas' Hospital on behalf of the Queen Elizabeth Military Hospital in 1991. Fifty-nine (63.4%) of procedures resulted in the patient's being recommended for further intervention. Sixteen (20%) of the 79 patients, thought to have ischaemic heart disease, had normal coronary arteries, but on further analysis of this group none could reasonably have been excluded from further investigation with angiography. Fewer military patients than civilians were recommended for active intervention. This probably reflects the fact that most of the military patients were under 50 years old, had had a myocardial infarction or angina and therefore warranted catheterisation because of their young age.