Prof. MUDr. Jan Janský (April 3, 1873, Prague – September 8, 1921) was a Czech serologist, neurologist and psychiatrist. He is recognized and credited with the first classification of blood into A, B, AB and O of the ABO blood group system.
Janský studied medicine at Charles University in Prague. From 1899 he worked in a psychiatric clinic in Prague. In 1914 he was named professor. During World War I Janský served two years as a doctor at the front until a heart attack disabled him. After the war he worked as a neuropsychiatrist in a military Hospital (Vojenská nemocnice). He had angina pectoralis and died of ischaemic heart disease.
Janský was also a proponent of voluntary blood donations.
