Early attempts to record medical microscopic images by photographic processes were done as soon as the technique was invented.

In 1840, Alfred Donné, free professor at the Faculté de medicine in Paris, took some photomicrographies adapting a daguerreotype camera to the microscope. With his assistant the physicist Léon Foucault, Donné published in 1845 a medical course “Cours de Microscopie” to be used by his students. An Atlas was also published, accompanying this publication, containing microdaguerreotypes of human fluids and tissues.

Despite this pioneering work it would be another ten years before photomicrography became implemented as a tool in medical research and teaching;questions were still raised on the use of microscopy for medical diagnosis.

The invention of the gelatin-dry plates in 1871 by the physician Richard Maddox, himself a keen microscopist, and improvements on optical equipment and artificial lights, led to an adequate use of photomicrography in medicine; by the end of the 1870s bacteria was being photographed. At the end of the 19th century the microscope had become a fundamental tool in medical research. Atlas, books and papers on the subject of photomicrography were then published and printed using mainly the half-tone process.

In Portugal the physician May Figueira (1829-1913) who studied in Paris, introduced microscopy and photomicrography in 1862 to his students in the Lisbon Medical School. By the end of the 19th century, microscopy was acknowledged in the country as an important tool to study diseases. The Portuguese bacteriologists Ricardo Jorge (1858-1939) and Anibal Bettencourt (1868-1930) made photomicrography a central tool for documenting their medical diagnosis.

In this paper we will discuss the role of the photomicrographic technique in diagnosis and in the illustration of medical scientific publications. Particular emphasis is placed on its impact on the development of bacteriology and histology.