Despite the increasing interest in Italian medicine, comparatively little attention has been paid to the establishment of iatrochemistry. Though this process spread throughout the Peninsula, Naples witnessed an impressive growth of chemical research and the outbreak of a conflict between the medical establishment and the chemical physicians. The purpose of this article is to explore the emergence of chemical medicine in Naples in the period that precedes the founding (1663) of the Accademia degli Investiganti. In the first part of the seventeenth century, chemistry achieved recognition in settings like academies, pharmacies, hospitals, and monasteries. Chemical studies and the making of new remedies were spurred by the scientific exchange that Neapolitan savants established with scholars from different areas. The so-called medical pluralism and the recurrent outbreaks of epidemics stimulated the introduction of new chemical therapies, which coexisted with old ones. The establishment of chemical medicine was triggered by Marco Aurelio Severino (1580–1656), who, besides promoting chemical remedies, resorted to chemical theories, including Paracelsian ones, to account for physiological processes. Severino was the mentor of the chemical physicians who gave rise to the Accademia degli Investiganti. One of Severino’s disciples was Giuseppe Donzelli (1596–1670), who fostered chemical remedies in Naples.