Prolonged administration of cycloheximide, an inhibitor of ribosomal protein synthesis, induces degeneration of rabbit taste bud cells: the degenerative changes resemble early changes in denervated taste buds. Our observations show that the pattern of degeneration is quite different in the three cell types of the taste buds. The earliest changes in type II and III cells are an increase in cytoplasmic filaments and extreme dilatation of rough endoplasmic cisternae. Profiles of dead type I and II cells vastly increase in number. Type I cells appear less affected by the drug and the only sign of degeneration was an increase in the number of autophagic vacuoles in their cytoplasm. There was no indication that degenerating type I cells undergo transformation to type II or III cells. These findings support our hypothesis that type I, II and III cells represent distinct cell types and do not undergo transformation to other types in the course of their life span.