Background:Heart failure (HF) is defined as failure of the heart to supply the blood essential for the metabolic demands of body.Children with heart failure represented 10% to 33% of all admissions.Recently, number of novel HF biomarkers have evolved.Soluble suppression of tumorigenicity 2 (sST2) is a member of the interleukin-1 receptor family which help in assessing the severity of HF and predicting the course of the disease. Aim of the work: Study the role of plasmasoluble suppression of tumorigenicity 2(sST2) in diagnosis and severityprediction ofpediatric heart failure either congenital or acquired. Patients and methods:The current comparative cross-sectional study included 45 pediatric cases ofheart failureand 45 healthy children as a control groupwith mean age of (7.19 ±5.33) and (8.87 ±5.38) years respectively. Both groups underwent full history taking, clinical examination, routine laboratory and radiological assessment including serum level of (sST2) and echocardiography. Results:Soluble suppression of tumorigenicity 2 (sST2) median level was statistically significantly higher among study group than control group (p