An ergonovine test (ET) was performed in 1,200 patients-742 men, 458 women aged from 34 to 73 years (mean: 49.5 years)-either during (850 cases) or after (350 cases) coronary arteriography. Another ET made more sensitive by blocking the cardiac autonomous nervous system (CANS) with labetalol 0.04 and 2 mg/kg was performed in 291 of these patients. The ET test was positive in 10.7 p. 100 (127) of all patients and in 11.2 p. 100 (127/1125) of patients presenting with retrosternal pain. In the group where spontaneous angina could be confirmed by ECG recordings during the attack, the percentage of positive responses rose significantly to 53.7 p. 100 patients with ST depression and 56.6 p. 100 of patients with ST elevation. When the anginal nature of the retrosternal pain was not confirmed before the test, the proportion of positive responses was 6.6 p. 100. In patients who had the sensitized test the positive response rate increased in all groups and globally rose significantly from 7.9 p. 100 to 18.6 p. 100 (p less than 0.01). Thus, the usually low frequency of positive ergonovine tests differs according to the population selected and increases after CANS blockade.