We describe direct and quantitative evidence of free-radical productio
n in the early stage after recanalisation in a patient undergoing prim
ary coronary angioplasty for acute myocardial infarction. After succes
sful initial dilation, the procedure was complicated by re-occlusion o
f the artery at the same site, with subsequent fall in free-radical ge
neration. After repeat angioplasty, recanalisation was again accompani
ed by increased free-radical production.