The invention relates to a medical probe for measuring radioactive radiation, comprising a housing that can be held single-handedly. A detector device (2) comprising a semiconductor diode is disposed in the housing and produces signals that interact with at least one of the following radioactive radiations: α, β?+, β-¿ and η radiation. A signal processing device (3) processes the signals produced by the detector device (2). A power supply device (4) provides the detector device (2) and the signal processing device (3) with power. The inventive probe is especially characterized in that a reproduction device (5) for reproducing the signals processed by means of the signal processing device (3) is mounted in the housing (1). The inventive device provides a compact measuring system that facilitates an (especially wireless) flexible intraoperative and extraoperative, local measurement of radioactively labeled tissue without requiring additional appliances.