Born in Budapest, Hungary, to a prosperous shopkeeping family of German origin, Semmelweis followed his undergraduate career at the University of Pest by earning his medical degree from the Vienna Medical School in 1844. After receiving his master's degree in midwifery, Semmelweis took a post as assistant in the Vienna General Hospital.

Semmelweis soon observed that the death rate among maternity patients in the ward treated by medical students was much higher (13%) than in the ward served by midwives (2%). When Semmelweis made a connection between the symptoms of a fatal dissection wound and puerperal fever, he concluded that the fever was transmitted to the maternity patients by medical students carrying infectious materials on their fingers from dissected cadavers. Starting in May 1847 Semmelweis required his students to wash their hands in a solution of chlorinated lime before examining patients. Mortality rates from puerperal fever promptly plunged.

In spite of these dramatic results, Semmelweis's colleagues rejected the concept that they could be responsible for spreading disease. Forced out of his Viennese post, Semmelweis abruptly returned to Budapest, where he was head of maternity at St. Rochus Hospital from 1851 until 1857. Here again he introduced antiseptic procedures and nearly banished puerperal fever.

Semmelweis finally published his findings in 1861, but critics continued to attack him fiercely and he reacted with increasing anger and bitterness. Mental illness overtook him in 1865; he died after only two weeks in an asylum of, ironically, sepsis from a surgical wound. That same year, Joseph Lister performed his first antiseptic operation.