In recent years metabolomics has facilitated gaining insight into discovering the potential disease diagnostic markers and observing fluctuations of certain metabolite levels in body fluids. Disease- related metabolites can be uncovered by following progress of the new methodologies which enable to identify a broad range of diagnostic biomarker candidates including amino acids. Owing to the vital roles of amino acids in metabolic regulations (protein synthesis, neurotransmission, hormone secretion, and immunity), they have become significant targets while taking snapshot of metabolic status. Therefore, elucidation of the circulating amino acids profile alterations by utilizing robust analysis method could shed light on not only in metabolic diseases but also in certain disorders such as autism, prostate cancer, Huntington’s disease, Parkinson’s disease, Alzheimer’s disease, obesity, type 2 diabetes, liver cirrhosis, major depressive disorder, and cardiovascular disease.