To this day one of the most curious gaps in the historiography of French psychiatry is the era between the fin-de-siècle and the 1920s, years that overlapped the life and career of Valentin Magnan (1835-1916), a pivotal figure in the historical classification of mental diseases. This paper seeks to address this shortcoming as well as contribute to the growing scholarly interest in the history of clinical psychiatry. It argues that Magnan was in many ways a tragic figure, someone who lived and worked at a time when circumstances conspired against him and his efforts to reform psychiatric classification. Essentially Magnan had the misfortune to practise psychiatry when Emil Kraepelin's influence began to spread beyond Germany's borders, sparking a nationalist reaction that penalized both French Kraepelinians and Magnan whose theories shared similarities with Kraepelin's. But Magnan's stature also suffered because of the intense internecine quarrels that arose in late nineteenth-century French psychiatry. Magnan was no helpless victim, though, and there is reason to believe that some of the criticism directed at him was based on documented personal failings. Ultimately, Magnan's theory of psychiatric classification was overtaken by these and other events in French psychiatry, culminating by the interwar period in the emergence of a new national, nosological pardigm that has dominated French psychiatry for most of the twentieth century. Thus Magnan was in many respects a pariah within French psychiatry by the early twentieth century. An examination of his career casts light on this crucial turning-point in the history of French psychiatry and indicates why and how the new model of classification was more to the tastes of his medical colleagues.