A simple technique is described for the rapid diagnosis of rabies in formalin-preserved brain. Brain tissue was emulsified, washed with phosphate-buffered saline and digested with trypsin. The digested material was stained according to conventional immunofluorescent procedures. Digestion with trypsin markedly enhanced the staining of rabies inclusions and eliminated non-specific staining of formalin-preserved brain. The method seems to be more accurate than histological examination.