Tibetan medicine presents a widely ramified classification of diseases relating to gender, age, humoral pathology, specific body regions or general systemic disorders. Different aetiologies of particular diseases are considered in Tibetan medicine - even if the biomedical context of many disease patterns remains unclear. The elaborated work of surgeon and anatomist Lozang Chödrak (Blo-bzang-chos-grags, 1638–1712?) organises medical content in the form of tree diagrams. In addition, his discourse explicitly lists names of diseases for passages where the classical text gives only numbers associated with certain pathological groups. His descriptions were visually realised in the form of 19 murals in the inner courtyard of the Medical College of Labrang Monastery, situated in present-day Gansu province of China. The five chapters on pathology are depicted by five trees that spread over three murals. Therein the Tree of Nosology, or classification of diseases, comprises three trunks, forty-three branches and hundreds of leaves, thus representing one of the most profusely illustrated sections of the Four Treatises. Elucidating the system underlying such classifications offers visual insights into the intellectual framework of Tibetan nosology.