Carbonization behavior of L-tryptophan and gluten has been investigated in comparison with that of acenaphthylene using CHN elemental analysis, wide angle X-ray diffractometry, laser Raman spectroscopy and polarizing light microscopy. The carbon derived from L-tryptophan by the heat-treatment at 3,000 degrees C showed almost the same degree of graphitization as that from acenaphthylene and the average interlayer spacings of both these carbons approached to 0.3354 nm. The average interlayer spacing of the carbon from gluten, on the other hand, did not approach to this value at 3,000 degrees C. The crystallites in the carbon from L-tryptophan were smaller than those in the carbon from acenaphthylene but larger than those in the carbon from gluten. The ratio, R, of the intensity of the Raman band at 1,360 cm(-1) against that at 1,580 cm(-1) and the half width, Delta lambda, of the Raman band at 1,580 cm(-1) were measured. The R and Delta lambda are the measures for the degree of graphitization. Those values for the carbon from L-tryptophan were nearly equal to those for the carbon from acenaphthylene and smaller than those for the carbon from gluten. The thin film of L-tryptophan heat-treated at 500 degrees C for 2 h showed a texture consisting of a fine mosaic mesophase structure and an anisotropic flow-type texture of mesophase.