The features of myocardial strains from speckle-tracking echocardiography (STE) have not been well defined in fulminant myocarditis (FM) patients. In this study, changes in the left ventricular ejection fraction (LVEF) and global and layer-specific myocardial strains over time were monitored. We aimed to determine the echocardiographic patterns of FM and ascertain their significance in FM treatment. Twenty patients who were clinically diagnosed with FM and received mechanical life support were prospectively enrolled. Conventional echocardiographic measurements were obtained, and serial strain echocardiography was performed from admission to hospital discharge until LVEF recovery (> 50%). Global/regional peak systolic longitudinal strains (GLS/RLS) and layer-specific longitudinal strains were quantified, and their changes with time were monitored in 14 FM patients. All patients had severely impaired cardiac function. Steep improvement in LVEF and GLS were observed within 6 days. Layer-specific strain analysis showed that reduction at admission or recovery at discharge in the endocardium and epicardium strains were equal. In conclusion, FM patients who received mechanical circulatory supports exhibited steep improvement in ventricular function within 6 days. The patchy and diffused distribution pattern of reduced RLS and equally and severely impaired strain in the endocardium and epicardium are valuable features in the diagnosis of FM.