Abstract: A system and method for determining the immune status or immune cycle in a subject is provided. A sampling component for obtaining physiological data from the subject is provided together with a data storage component for storing the physiological data obtained from the subject. A processing component is provided to analyse the physiological data and thereby determine the immune status or periodicity of the immune cycle and the immune cycle of the subject. An output component for outputting the immune status or periodicity of the immune cycle, and the immune cycle of the subject and/or the future status or immune cycle of the subject is provided.