We investigated the response to high hydrostatic pressure (HHP) of mammalian cells, since HHP is proposed to be suitable to inactivate mammalian cells in biopharmaceutics and patient's material. We observed that cells were not restricted in their viability by pressures up to 100 MPa. Mammalian cells die when treated with pressures of 200 MPa or more. But the effects of 200, 300 or 400 MPa do not follow the same pattem. At 200 MPa, cells die in a way that is related to apoptosis. Some apoptotic characteristics like phosphatidylserine (PS) exposure and morphological alterations appear very fast. Other features like a higher exposure of intracellular NPn ligands and pronounced degradation of DNA and lectin ligands are unique features of HHP induced apoptosis. Cells treated with 300 and 400 MPa die immediately following a unique necrotic pathway, since treated cells harbour high DNA and glycoprotein degrading activities.