Abstract:The concepts of disturbing fuzzy grammars and their languages are introduced, the related Chomsky class if cation is discussed, and it is shown that disturbing fuzzy weak regular grammar, disturbing fuzzy regular grammar and distur- bing-valued fuzzyfnite-state automata are equivalent. The notions of disturbing fuzzy context-free grammar, leftmost deriva- tion, Chomsky normal form and Greibach normal form are given, and the unanimity of their languages is revealed.