AbstractA microwave version of Steiner's method for demonstrating spirochetes and bacteria is described. The method differs froi Steiner's method and its modifications in that the concentration of the uranyl nitrate and silver nitrate solutions was reduced from 1% to 0.5%. Decreasing the concentration of the uranvl nitrate solution reduces exposure to this radioactive substance. Uranyl nitrate sensitization, silver nitrate impregnation, and the reduction were performed by microwave irradiation at temperatures well below the boiling point of the solutions. The entire procedure took about ten minutes to perform with even, consistent silver impregnation of the organisms. (The J Histotechnol13:45, 1990)