Alogliptin, a dipeptidyl peptidase-4(DPP-4) inhibitor, is launched in Japan in advance of other countries in the world. Alogliptin has high-selectivity to inhibit DPP-4 activity compared to other DPP-4 inhibitors due to its unique formula of chemical structure. Clinical studies provided evidences that alogliptin monotherapy with daily doses of 12.5 and 25 mg decreased the HbAlc level approximately 0.4-0.8% accompanied with an elevation of active glucagon-like peptide(GLP)-1 level. Neither body weight change nor apparent adverse events was observed. In type 2 diabetic patients who already treated with pioglitazone or voglibose, addition of alogliptin further decreased HbAlc by 0.9% from basal level during 12-week study period. Here, we entirely reviewed pharmacological and clinical profiles of alogliptin by introducing preclinical and clinical studies conducted inside and outside of Japan.