Jan Jansk� (3. 4. 1873 - 8. 9. 1921) - Czech physician, neurologist and psychiatrist. One of the first described by dividing into the human blood groups. Jansky was also a promoter of blood donation. Jan Jansky was born in Sm�chov. After graduating from the local grammar school, he joined the Medical Faculty of Charles University, where he graduated in 1898. The following year he became a doctor at a psychiatric clinic in Prague and in 1914 there was appointed a deputy chief. Everything has changed but the First World War, after which he worked outbreak Jansk� as front-line physician. In 1916, however, suffered a heart attack and was therefore released from service. After the war he became head of the neuropsychiatric department at the Military Hospital in Prague.

At the beginning of his career psychiatrist dealt hypothesis that moha be a link between blood coagulation and mental disorder. Disproved this theory and research results compiled in technical treatise (1906), published in 1907 in the Proceedings of clinical. Here also first described the separation of blood into four groups. Jansk� But the importance of his discovery probably does not realize, because they also did not continue in this direction and focused on neurology and psychiatry.

Similar conclusions reached independently of other researchers: Jansk� ago it was mainly Viennese biologist Karl Landsteiner: one defined but only three blood groups. In 1910 published the results almost identical to research Czech doctor, American immunologist Moss. About Jansk�ho did not work, but later acknowledged his leadership in the correct classification of blood groups.

Jan Jansk� died at only forty-eight years on the effects of chronic heart disease in �erno�ice near Prague.

Voluntary donors in the Czech Republic awarded a plaque Jana Jansk�ho in three categories: bronze for ten donations, silver and gold for twenty forty contributory donations. Similar Jansk�ho awards are granted and the Slovak Republic.