The invention relates to a method for producing cellulosic forms, such as fibres, filaments, films, membranes or tubes by a) extruding a solution of cellulose in a hydrous amine oxide, especially N-methylmorpholine-N-oxide, through a moulding tool, over an air gap, and coagulating the form in an aqueous precipitating bath containing amine oxide and b) guiding the form through at least one washing stage in order to remove the residual amine oxide. The method is characterised in that the precipitating bath liquid and/or the washing liquid are treated with ultraviolet radiation in the precipitating stage and/or in the washing stage(s) respectively. This prevents the formation and spread of coatings, films and secretions of slime formed by micro-organisms on the parts of the system that come into contact with the NMMO-containing liquor.