De Baillou is an important figure in medicine, and as he was the first physician to describe whooping cough, he deserves to rank high among those who have contributed to the development of pediatrics. Crookshank calls him the first epidemiologist of modern times. He came of good stock, his father, Nicolas, being celebrated both as a mathematician and as an architect. He studied in the University of Paris, and received his bachelor's degree in 1568 and his doctor's degree in 1570. From that time until his death in 1616, at the age of 78, he practiced in his native city.
As a teacher, de Baillou attained a reputation not only for imparting knowledge, but for his severity in examinations; this earned for him the title of "fleau des bacheliers." In 1580, he was made "doyen" by the faculty of Paris. Henry IV appointed him physician to the Dauphin, but he