Method for electrophoretic separation of nucleic acid fragments comprising the following steps: a) providing a polyacrylamide based gel prepared by photoinitiated polymerization of a mixture containing monoolefinic- and di- and/or polyolefinic monomers and a photoinitiator of the general formula: ##STR1## where R.sub.1 and R.sub.2 independently are CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7 or R.sub.1, R.sub.2 together with the carbon atom form a cycloaliphatic ring with 4-8 carbons; R.sub.3 =H, CH.sub.3, C.sub.2 H.sub.5 or --O--(CH.sub.2 CH.sub.2).sub.n --OH with n=1-20; b) applying said nucleic acid fragments on said polyacrylamide based gel; c) electrophoretically separating said fragments on said gel. The invention also relates to a kit for use in the method for electrophoretic separation of nucleic acid fragments.