This chapter utilises data gleaned from botanical treatises, missionary accounts and official correspondence to approach diagnostic categories in early modern medicine in Angola. It also discusses early modern constructions of mental pathology. West-Central African history is exceptional in providing ample primary sources for discussing health and disease in Africa prior to the nineteenth century. The documentation abounds with contemporary social diagnoses of diseases in West-Central Africa occasionally written by physicians or surgeons, but almost as often uttered by colonial administrators, priests, naturalists and common people. Yet, they are often of little use in determining the modern biological diagnoses. Essentially, they point out that humoural theory was rarely a reference point when making social diagnoses. Instead, laypeople and doctors usually referred to very general symptoms and conditions. The Portuguese understanding of epidemic diseases remained extremely limited throughout the era of the slave trade.