With mental health becoming increasingly visible across the Western world during recent years, the question of where our often-stigmatising attitudes towards mental illness stem from is of paramount importance. This paper examines how mental illness was depicted in medical and fictional literature from the late-nineteenth century in France, a period during which the categorisation, perception and treatment of mental illnesses evolved significantly. This research compares the portrayal of mental illness in the fictional literature of Émile Zola, a prolific nineteenth-century French writer, with prominent French medical journals from this period. Both of these genres of text reflect the then-widespread public fascination for conditions such as hysteria, and weave discourses about gender roles and concerns about population decline as well as familial deterioration into their depictions of mental illness. By representing psychological disorders as a danger to the traditional family unit, and as intimately linked with the female menstrual cycle and expressions of female sexuality, these texts allow us to evaluate nineteenth-century perceptions of gender norms, reproduction and the family. This comparative research demonstrates that the interaction of medical and literary portrayals of ‘madness’ holds up a mirror to late nineteenth-century French society and therefore contributes to efforts within the medical humanities field to put modern-day perceptions of mental illness into context.