Abstract MIMOSIS is a CMOS Monolithic Active Pixel Sensor (CPS) developed to equip the Micro Vertex Detector (MVD) of the Compressed Baryonic Matter (CBM) experiment at FAIR/GSI. The sensor will combine a spatial resolution of -5 µm with a time resolution of 5 µs and provide a peak hit rate capability of ∼80 MHz/cm 2 . To fulfil its task, MIMOSIS will have to withstand ionising radiation doses of ∼5 MRad and fluences of ∼7 × 10 13 n eq /cm 2 per year of operation. The paper summarises major requirements of the CBM-MVD and compares them to the detection performances of the first full scale prototype, called MIMOSIS-1, recently evaluated in the laboratory and with particle beams. The tolerance of the sensor to the expected ionising radiation load was evaluated; the paper describes the measurements performed and their outcome.