We compared the sensitivity of three commonly used provocative tests, exercise, ergonovine and the cold pressor test, in a series of 34 hospitalized patients with well-documented, active variant angina. All tests were performed off medication at the same time of day, usually on 3 consecutive days. Angina was provoked by ergonovine in all 34 patients, by exercise in 17 and by the cold pressor test in only 5 (p less than 0.005). ST elevation developed during the ergonovine test in 32 (94%), during exercise in 10 (29%) and during the cold pressor test in only 3 (9%). With ergonovine one patient had ST depression only and one had no ECG changes. During the cold pressor test two patients had pseudonormalization of abnormally negative T waves and 29 had no ECG changes. Exercise induced T wave pseudonormalization in 4 patients, ST depression in 9 others and no ECG changes in 11. Thus, in patients with active variant angina, the sensitivity of the cold pressor test and exercise are too low to be useful clinically. Other studies suggest that the sensitivity of hyperventilation or provoked alkalosis is higher, but not as high as ergonovine administration. In patients who have become asymptomatic, either with treatment or spontaneously, the sensitivity of all tests decreases markedly. If such patients no longer have coronary spasm, the test is not a 'false negative' but a 'true negative'. Deaths have been reported following ergonovine administration and for this reason the test is not universally accepted.(ABSTRACT TRUNCATED AT 250 WORDS)