A simple new method of deep-etching, 'upside-down etching', has been developed in an attempt to obtain clearer images or replicas, especially of fresh, untreated biological tissues. During etching, specimens were kept facing downwards and shaken periodically so that non-volatile materials in the subliming ice could fall out of the frozen tissue. This improvement leads to a considerable reduction of sedimented debris of unetchable materials on 'true' membrane surfaces, as well as in the cytoplasm exposed by deep-etching.