This study focuses on medical prognostication in the earliest Indian medical treatise known, the Caraka Saṃhitā. The first chapter gives an overview of the Caraka Saṃhitā, including its main doctrines and philosophy. The second chapter introduces the Indriyasthāna, the section in the Caraka Saṃhitā in which most of the omen literature is collected. The third chapter gives a survey and preliminary analysis of all twelve chapters in the Indriyasthāna. In the final chapter and conclusion, the topic of omen literature in the ancient world in general will be discussed, with a focus on the issue that invariably presents itself in omen literature, “rationality.” / text