As vegetative forms of microorganisms are impaired by high hydrostatic pressure (HHP) in the range of 400-600 MPa, the non-thermal inactivation of vegetative bacteria, yeasts, and moulds present in foods such as jams, fruit juices, and dressings by HHP is now well-established. Eukaryotic cells, when subjected to HHP are also damaged. In the present study, the effect of HHP on cell viability of human osteoblasts (HOB), human fibroblasts (HFB), and different tumor cell lines such as osteosarcoma cells SAOS-2, human histiocytic leukemia cells U-937, and the ovarian cancer cell line OV-MZ-6 was investigated. Therefore the different cell lines were subjected to pressures between 50 and 400 MPa and tested for viability. At HHP of 100 MPa (10 min) about 80% of the various cell lines were still alive. At 350 MPa all of the cells were damaged and dead. The three tumor cell lines investigated were slightly more resistant to HHP (50% dead at 170-193 MPa) than HOB and HFB (50% dead at 130-145 MPa). The present study demonstrates that both normal cells and tumor cells are rapidly inactivated by HHP treatment.