AbstractA microwave stimulated diffusion method for preparing hamster and human oral mucosal tissue block for paraffin sections within 15 min is described. The dehydration, clearance, and impregnation time was saved by a factor of 34 for animal tissue and a factor of 103 for human tissue. Light microscopically, the results were excellent and indistinguishable from those of tissues prepared by the classical method. The new method is valuable for infectious cases requiring urgent diagnosis; they can be performed without frozen sections that require unfixed fresh tissue and sometimes produce inconsistent results. Moreover, the microwave processing technique is practical in small research laboratories as a microwave oven is the only equipment required. (The J Historechnol13:127, 1990)