The invention refers to a composition for the fixation of histological preparations, comprising a solution of glyoxal, wherefrom acids, normally present in the commercially available glyoxal, have been removed. The composition of the invention provides an optimal fixative for the preservation of structure, antigenic components and nucleic acids in tissues. The acid-free glyoxal has limited toxicity, is not considered as a carcinogenic agent and represents a valid alternative to formalin for the fixation of tissues and cells.
