A method for analysis of large restriction fragments of DNA with a high degree of confidence of finding mutations. The large fragment is separately digested with several cocktails (preferably five) of endonucleases. The resulting digests are denatured, mixed together, labelled and electrophoresed on non-denaturing gels. In the restriction component of the analysis, additional or absent electrophoretic bands, compared with normal DNA, will result when a mutation creates, destroys or changes the electrophoretic mobility of a band.