Prevalence of type 1 silent myocardial ischemia (SMI; completely asymptomatic patients) is reported to appear 2 to 4% of the general population. The prognosis of these patients is said to be similar to that of patients with angina pectoris. Our study investigated a 10-year follow up of silent myocardial ischemia detected by bicycle exercise testing in comparison to a comparable control group. 10 years later 127 patients were reinvestigated by bicycle ergometry, 33 patients out of the SMI-group (group A) and 84 patients out of the control group (group B). Mean age in group A was 62 +/- 7 years (range 42 to 71 years), in group B 56 +/- 7 years (range 29 to 69 years). After 10 years there was no statistical significant difference between the 2 groups on using beta-blockers, calciumchannel-blockers and nitrates, on arterial hypertension, diabetes mellitus, smoking history and positive family-history as well as in total cholesterol, HDL- and LDL-cholesterol, triglycerides, blood glucose and uric acid. 1 patient of A and 2 of B died from a sudden cardiac death, 2 of A and 7 of B survived a myocardial infarction, 11 of A and 11 of B developed angina pectoris (p < 0.05). A statistical significant difference was found in the ergometric working capacity (maximal workload in Watt) between the 2 groups (p < 0.001) that did not change over the 10 years, the control group worked better in both investigations. SMI type 1, detected by bicycle ergometry seems to be only a risk factor for developing "loud ischemia" (= angina pectoris) but not for "hard events". A routine screening of completely asymptomatic persons with bicycle ergometry seems to have no prognostic relevance.