D-2-hydroxyacid dehydrogenases are a group of evolutionarily related oxidoreductases that catalyze stereospecific, reversible reduction of 2-keto acids to the corresponding 2-hydroxy acids, using NAD+ or NADP+ as an electron acceptor: `R-CO-COOH + NAD(P)H + H+ ⇋ R-CH(OH)-COOH + NAD(P)+`. Although 2HADHs can be divided into evolutionarily related subfamilies sharing similar substrate specificity, the exact biological function of the majority of 2HADHs is unknown. In our study, we revised the previous classification and systematically analyzed the collected biochemical and structural data. For more details, please see: Matelska D, Shabalin IG, Jabłońska J, Domagalski MJ, Kutner J, Ginalski K, Minor W. Classification, substrate specificity and structural features of D-2-hydroxyacid dehydrogenases: 2HADH knowledgebase. BMC evolutionary biology,18:199 (2018).