Single crystals of L-lysine-doped TGS (LLysTGS) have been prepared from the aqueous solutions with various concentrations of dopant. The variation of crystal shape and the distribution of internal bias field E-b were examined. The growth rate in the + b side of seed crystal is higher than in the -b side. Therefore, the mirror plane in normal to the ferroelectric b-axis disappears in the crystal morphology and the doped crystal shows a habit of polar symmetry 2. The degree of the asymmetry increases with the concentration Of L-lysine. The effect Of L-lysine-doping on the crystal shape is closely resembled to the L-alanine-doping (LAlaTGS). The internal bias field Eb caused by the doping depends on the growth sector. The distribution of Eb also shows the symmetry 2. There exist both sectors with positive Eb and negative Eb. The development of Eb in LLysTGS crystal is distinctly different from that in LAlaTGS. (c) 2007 Elsevier B.V. All rights reserved.