The aim of the study was to evaluate the effects of 0.9% NaCl and other solutions suitable for peritoneal lavage on in vitro viability and fibrinolytic activity of human peritoneal mesothelial cells.Material and methods. Mesothelial cells were isolated from the intra-operatively collected greater omentum specimens and then cultured. Subsequently, eight cultures (n=8) were incubated for six hours with M199 culture medium (control group) or culture medium with the addition of 0.9% NaCl, PD fluid Gambrosol-Trio 10 or Hanks' solution. Immediately after exposure to the studied solutions, the amount of LDH released by the cultured cells was determined. Then, cultured cells were incubated for the next 24 hours; after this period their metabolism and fibrinolytic activity were determined by means of IL-6, t-PA and PAI-1 levels. Levels of these substances were compared to the amount of total cellular protein that was determined simultaneously.Results. Hanks' solution showed no significant influence on cellular culture architecture and mesothelium metabolism. PD fluid Gambrosol-Trio 10 damaged mesothelial cell structure and function as manifested by an increased release of LDH and enhanced t-PA synthesis, as well as decreased production of IL-6 and PAI-1. Exposure to 0.9% NaCl solution was found to cause a disturbance in cellular adhesion without significant structural damage (marked changes in cellular morphology without increased LDH release) and significant metabolism impairment as presented by reduced production of t-PA, IL-6 and PAI-1.Conclusions. Saline solution and PD fluids should not be used for peritoneal lavage. Further investigations are required to identify the least harmful solution for mesothelial cells suitable for application in intra-operative peritoneal lavage.