The textbook on pathology of candidate of theology priest Mikhail Legeev covers the period of patristic writing of the Ancient Church (I-III centuries). The book is built on the principle of chronological presentation of the material. The author's approach is based on a conceptual vision of the historical development of patristic thought as a whole. Each topic presented, dedicated to any of the outstanding fathers and teachers of the Church, reflects the most striking, characteristic features of their work.