Hyper-homocysteinaemia is a cardiovascular risk factor. In parallel, anatomopathological studies of post-angioplasty coronary restenosis show histological appearances similar to those observed in patients with severe hyper-homocysteinaemia. Based on these histological observations, the authors tried to assess the predictive value of raised plasma homocysteine levels for coronary restenosis after angioplasty. Two hundred and twenty-two patients treated by coronary angioplasty were followed up clinically for 6 months. Thallium 201 myocardial scintigraphy was performed in 179 patients and coronary angiography in 74 patients. Seventy-nine patients had coronary restenosis diagnosed by coronary angiography in 55 cases, by myocardial scintigraphy in 23 cases and strongly suspected clinically in only one patient. No significant differences in homocysteine levels were observed between patients with multiple restenosis or requiring revascularisation, and those without restenosis and not requiring revascularisation. Plasma homocysteine does not therefore seem to be a predictive factor of post-angioplasty coronary restenosis.