It is common practice to hospitalize patients with chest pain for a period of observation and to perform further diagnostic evaluation such as exercise treadmill testing (ETT) once acute myocardial infarction (AMI) has been excluded. This study evaluates the safety and efficacy of immediate ETT for patients admitted to the hospital with acute chest pain. One hundred and ninety non-consecutive low-risk patients admitted to the hospital from emergency department with acute chest pain underwent ETT using Bruce protocol immediately on admission to the hospital (median time 165+30 min). Fifty-seven (30%) patients had positive exercise electrocardiograms, 44 (77.2%) of whom had significant coronary narrowing by angiography. An uncomplicated anterior non-Q-wave AMI was diagnosed in one patient. One hundred and eleven (58.4%) patients had negative and 22 (11.6%) patients had non-diagnostic exercise electrocardiograms. Of these 133 patients, 86 (64.7%) were discharged immediately after ETT, 19 (14.3%) were discharged within 24 h, and 28 (21%) were discharged after 24 h of observation. There were no complications from ETT. During the 17+/-6 months follow-up no patients died, and only eight (7.2%) patients with negative ETT experienced a major cardiac event (one AMI and seven angina). In conclusion, our results suggest that immediate ETT of low-risk patients with chest pain who are at sufficient risk to be designated for hospital admission, is effective in further stratifying this group into those who can be safety discharged immediately and those who require hospitalization.