IMPORTANCE: The incremental benefit of noninvasive testing in addition to clinical evaluation (history, physical examination, an electrocardiogram [ECG], and biomarker assessment) vs clinical evaluation alone for patients who present to the emergency department (ED) with acute chest pain is unknown. OBJECTIVE: To examine differences in outcomes with clinical evaluation and noninvasive testing (coronary computed tomographic angiography [CCTA] or stress testing) vs clinical evaluation alone. DESIGN, SETTING, AND PARTICIPANTS: This study was a retrospective analysis of data from the randomized multicenter Rule Out Myocardial Ischemia/Infarction by Computer Assisted Tomography (ROMICAT-II) trial. Data for 1000 patients who presented with chest pain to the EDs at 9 hospitals in the United States were evaluated. INTERVENTIONS: Clinical evaluation plus noninvasive testing (CCTA or stress test) vs clinical evaluation alone. MAIN OUTCOMES AND MEASURES: Primary outcomewas length of stay (LOS). Secondary outcomes included hospital admission, direct ED discharge, downstream testing, rates of invasive coronary angiography, revascularization, major adverse cardiac events (MACE), repeated ED visit or hospitalization for recurrent chest pain at 28 days, and cost. Safety end points were missed acute coronary syndrome (ACS) and cumulative radiation exposure during the index visit and follow-up period. RESULTS: Of the 1000 patients randomized, 118 patients (12%) (mean [SD] age, 53.2 [7.8]; 49 [42%] were female) did not undergo noninvasive testing, whereas 882 (88%) (mean [SD] age, 54.4 [8.14] years; 419 [48%] were female) received CCTA or stress testing. There was no difference in baseline characteristics or clinical presentation between groups. Patients who underwent clinical evaluation alone experienced a shorter LOS (20.3 vs 27.9 hours; P < .001), lower rates of diagnostic testing (P < .001) and angiography (2%vs 11%; P < .001), lower median costs ($2261.50 vs $2584.30; P = .009), and less cumulative radiation exposure (0 vs 9.9 mSv; P < .001) during the 28-day study period. Lack of testing was associated with a lower rate of diagnosis of ACS (0% vs 9%; P < .001) and less coronary angiography and percutaneous coronary intervention (PCI) during the index visit (0% vs 10%; P < .001, and 0% vs 4%; P = .02, respectively). There was no difference in rates of PCI (2%vs 5%; P = .15), coronary artery bypass surgery (0% vs 1%; P = .61), return ED visits (5.8% vs 2.8%; P = .08), or MACE (2%vs 1%; P = .24) in the 28-day follow-up period. CONCLUSIONS AND RELEVANCE: In patients presenting to the ED with acute chest pain, negative biomarkers, and a nonischemic ECG result, noninvasive testing with CCTA or stress testing leads to longer LOS, more downstream testing, more radiation exposure, and greater cost without an improvement in clinical outcomes.