Human galectin-3 is a 35 kDa protein that is coded by a single gene, LGALS3, located on chromosome 14. The N-terminal domain of galectin-3 is essential for its multimerization, sensitive to proteolysis by matrix metalloproteinases and may participate in the interaction with other intracellular proteins. Furthermore, the first 12 amino acids of galectin-3 are necessary for its secretion and nuclear translocation. The C-terminal CRD of galectin is responsible for its interaction with glycoconjugates containing N-acetyllactosamine. Thus, galectin-3 binds proteins in a carbohydrate-dependent and -independent manner. Galectin-3 is pivotal in numerous biological activities including cell growth, apoptosis, pre-mRNA splicing, differentiation, transformation, angiogenesis, inflammation, fibrosis and host defense. Both increased and decreased expression levels of galectin-3 are observed in various types of disease including heart, renal and liver disease, cancer and infections. Its prognostic value in predicting the outcomes of Heart failure (HF) and its diagnostic value in thyroid carcinoma diagnosis have been extensively investigated, and indicate its potential application for HF prognosis and thyroid carcinoma diagnosis.