One pot ligation of peptide segments is an effective approach to improve the efficiency of chemical synthesis of proteins. We recently found that peptide hydrazides were useful surrogates for peptide thioesters as intermediates for protein chemical synthesis. In the present meeting I wish to discuss the problems and potential solutions for the one pot ligation of peptide hydrazides. An example will be given for the use of new one pot ligation method to synthesize modified histone proteins.