Transthoracic echocardiogram (TTE) is widely used as part of the work-up for ischemic stroke. However, the added utility of TTE in the management of small single subcortical infarcts (SSSI) has not been extensively evaluated. Therefore, we aimed to determine the frequency of high-risk and medium-risk cardioembolic sources diagnosed by TTE in SSSI patients, and whether the findings altered clinical management. We performed a retrospective analysis of a prospective cohort of patients with confirmed acute ischemic stroke enrolled in a single-center observational registry between August 2012 and July 2014. We assessed infarct topography on brain magnetic resonance imaging, blinded to final stroke subtype and treatment, to identify patients with SSSI. We defined SSSI as lesions in the corona radiata, basal ganglia, thalamus, or brainstem measuring <1.5 cm in maximal diameter. We excluded patients with atrial fibrillation and large artery stenosis >50%, and assessed the frequency of cardioembolic sources found by TTE in the remaining patients. Among 908 patients, 75 (8.3%) had SSSI, of which 4 (5.3%) had atrial fibrillation and 6 (8%) had symptomatic large artery stenosis. TTE revealed cardiac abnormalities in 46% of the remaining patients (mean age: 65.1 y, 52% female, 58% white). The most common findings were dilated left atrium (29%), patent foramen ovale (14%), and atrial septal aneurysm (7.7%). Anticoagulants were prescribed in 3 (4.6%) patients on the basis of TTE results. TTE identified potential cardioembolic sources in almost half of the patients, but altered antithrombotic management in only 5% of patients with SSSI.