The invention relates to a fixing solution for in vitro preservation of a cell sample including nucleated cells and red blood cells, wherein said solution includes alcohol for fixing the cells. Said fixing solution includes physiological serum so as to avoid osmotic shocks in the cell walls and moreover contains formol and polyethylene glycol for preserving the size and integrity of the nucleated cells and red blood cells that are fixed in said solution. The solution does not contain compounds from either the ketone or acetic acid families.
