As a physician at a home for incurables in Abbiategrasso, Italy (1872–75), and with only rudimentary facilities at his disposal, Golgi devised (1873) the silver nitrate method of staining nerve tissue, an invaluable tool in subsequent nerve studies. This stain enabled him to demonstrate the existence of a kind of nerve cell (which came to be known as the Golgi cell) possessing many short, branching extensions (dendrites) and serving to connect several other nerve cells. The discovery of Golgi cells led the German anatomist Wilhelm von Waldeyer-Hartz to postulate, and Ramón y Cajal to establish, that the nerve cell (neuron) is the basic structural unit of the nervous system, a critical point in the development of modern neurology.

Turning to the study of malaria (1885–93), Golgi found that the two types of intermittent malarial fevers (tertian, occurring every other day, and quartan, occurring every third day) are caused by different species of the protozoan parasite Plasmodium and that the paroxysms of fever coincide with release of the parasite's spores from red blood cells.