The invention relates to a system for monitoring the reproductive activity of animals where a male mounts a female in order to mate, this system can determine the following information each time a male mounts a female, namely: whether or not the male has ejaculated, the date and time of ejaculation, and the identification of the female mounted. The system comprises an electronic sensor device placed on male animals, a radio-frequency identification tag placed on female animals, a system for preventing multiple or erroneous readings, and an electronic hand-held device for collecting information and configuring devices. The invention also includes a communication system and a central system that manages and concentrates all of the information, allowing the user to access said information in an organised, centralised and systematic manner.