The aim of this study is to identify the signs and symptoms of patients admitted for decompensated heart failure (HF) in order to infer the priority nursing diagnoses (ND). This is a cross-sectional study undertaken in a university hospital. The data were collected by nurses trained to deal with HF and registered in a file containing identification items, and demographic and clinical variables. We included 303 patients. Most patients were in emergency departments (95.7%) with functional class III (65.7%). The signs and symptoms identified at the time of admission were dyspnea (91.4%), paroxysmal nocturnal dyspnea (87.5%), fatigue (67.3%), edema (63.7%), orthopnea (55.4 %) and jugular vein distention (28.7%). From the signs and symptoms raised, that became the set of relevant clues and consistent as an indicator for ND, we conclude that Decreased Cardiac Output and Fluid Volume Excess diagnoses were the priorities for this population.