This first ever account of the history of the Italian patent legislation throughout the nineteenth century describes the salient characteristics of patent systems in the Italian pre-unitary States (Kingdom of Sardinia, Gran Duchy of Tuscany, Lombardo-Veneto Kingdom, Kingdom of the Two Sicilies, etc.). It assesses the extent to which the legacy of these pre-unitary states’ legislation shaped the discussions and the formation of the first Italian patent law after the political Unification in 1861. It then compares the characteristics of the Italian patent law of 1864 with the English, French, and German models, noting that this 1864 law remained substantially unchanged until 1934. Finally it examines, from an Italian perspective, the implementation of the Paris Convention of 1883 in terms of both legislative changes and its effects on the activities of indigenous and foreign inventors in Italy, providing an analysis of the major trends in patenting activities by Italian and foreign inventors and their changes over time.