Acute heart failure (AHF), a common and growing health concern worldwide, is associated with high risk of post-discharge rehospitalization and mortality. Existing evidence indicates potential therapeutic benefits of serelaxin in Caucasian AHF patients, but corresponding data in Asians remain scarce. RELAX-AHF-ASIA, a multinational, randomized, double-blind, placebo-controlled, phase III trial, will evaluate the effects of serelaxin on symptom relief and clinical outcomes in Asian AHF patients, with the use of novel assessments.