Ivan Pavlov (1849–1936) and Santiago Ramón y Cajal (1852–1934) were two contemporary scientists who not only had a great impact on Russian and Spanish science but also on the international stage. Both shared several common features in their life and work, yet they followed fundamentally different paths during their training as scientists. While Pavlov received his laboratory training under the guidance of Ilya Tsion (1843–1912), Cajal did not receive any formal training within a particular laboratory nor did he have a mentor in the traditional sense, rather he was mainly self-taught, although he was supported by key figures like Maestre de San Juan (1828–1890) and Luis Simarro (1851–1921). In this article, we compare the scientific training of these two Nobel Prize laureates and the influences they received during their scientific lives.