We evaluated the repeatability of some measurements taken during the bicycle ergometer exercise test (exercise duration, heart rate and pressure rate product at angina and ST segment depression times) in 166 consecutive non-selected ambulatory patients with proven ischemic heart disease. One hundred and sixty-six patients with history of angina and/or myocardial infarction performed three exercise tests within seven days of wash-out. Eighty-six (58.1%) of these experienced angina and ischemic ST segment depression during all three tests (group 1), and 80 (48.2%) finished at least one test without angina or ST segment depression (group 2). The degree of angina (according to Canadian Cardiovascular Society classification) was higher in the first group than in the second one; on the contrary, exercise duration as well as pressure rate product at ischemic threshold, heart rate and pressure rate product at the onset of angina were significantly lower (0.001 less than p less than 0.05) in the former group. In group 1, we analyzed ergometric parameter measurement "repeatability" during the three consecutive exercise tests. The analysis of variance for repeated measurements showed that exercise duration and pressure rate product values at ischemic threshold did not vary significantly in the three tests, while other ergometric parameters showed a greater variability (0.001 less than p less than 0.05). Age, previous myocardial infarction or rest angina, the number of critically stenotic coronary vessels and the ejection fraction did not condition the repeatability of the test. In conclusion, in our population of non-selected ischemic patients only 52% developed angina and ischemic ST segment depression during all three exercise tests performed.(ABSTRACT TRUNCATED AT 250 WORDS)