Single crystals of triglycine sulfate (TGS) doped with L- D- and DL-methionine have been prepared Doping effects on the crystal morphology the ferroelectric domain structure and the generation of Internal bias field E-b were investigated These effects were compared with each other and also compared with those of alanine-doped crystals Though L-methionine-doped crystals show the asymmetric morphology analogous to L-alanine-doped crystals these two crystals are distinct from each other in their domain structure and the generation of Eb It was ascertained that the asymmetry caused by L- and D-methionine are mutually reversed in the b-axis For the doping of racemic mixture DL-methionine we could recognize the overlap of doping effects caused by the both enantiomers of methionine (C) 2010 Elsevier B V All rights reserved