The incremental prognostic value of dual-isotope myocardial perfusion scintigraphy using technetium-99m tetrofosmin for the stress images was evaluated in 597 consecutive patients with known or suspected coronary artery disease. We used semi-quantitative visual analysis with a five-point scoring system and calculated the summed stress score, the summed rest score and the summed difference score. During the 2-year follow-up period, 46 "hard" cardiac events occurred: 16 cardiac deaths and 30 non-fatal myocardial infarctions. Kaplan-Meier analysis demonstrated a favourable prognosis for patients with normal scans as compared with patients with mildly to moderately or severely abnormal scans ( P<0.001). Multivariate analysis demonstrated incremental prognostic information for nuclear variables. A very low rate of hard cardiac events was observed in patients with a low summed stress score. Thus, nuclear variables provide incremental prognostic information and could be used to guide the management process with respect to whether or not to proceed with further invasive procedures.