We performed coronary artery spasm provocation, using the cold pressor test (CPT) and hyperventilation (HVT) in 105 patients (87 males, 18 females) with mean age 51.9 years (range 25-69) consecutively admitted for coronary angiography due to attacks of chest pain. A positive response to spasm provocation (ST segment elevation or depression greater than or equal to 0.1 mV or pseudonormalization of negative T-waves) was seen in 25 patients (23.9%) (group A), with 8 patients responding to CPT and 23 to HVT. In the remaining patients (group B) a negative response was found. Of 80 patients with coronary artery stenosis (diameter reduction greater than 50%), 22 (27.5%) showed a positive response. During CPT and HVT the rate pressure product increased 25% and 16%, respectively in group A versus an increase of 139% during exercise testing in the same patients. This suggests that ischaemia induced by CPT or HVT is not caused by increased myocardial oxygen demand. Repeat spasm provocation was performed during coronary angiography in 14 patients from group A and 14 from group B. The induced reduction in the diameters of the ischaemia related vessels was on average 48.3% in group A versus a 9.9% reduction of the left anterior descending artery in the patients from group B (P less than 0.01). In group A 88% had a history of nocturnal angina versus 38.8% in group B (P less than 0.001). A positive exercise test was found in 87% and 35.6% in group's A and B respectively (P less than 0.0005).