A simple and economical staining method for isozyme is described. Filter paper (treated with 0.4% agarose) was soaked in isozyme staining solution for half an hour and was used to stain the isozymes after PAGE, then move the gel and filter paper to a covered plastic box.The staining time would be longer than normal. After staining, put the gel and filter paper into fixing solution and remove the filter paper with tweezers carefully.