alpha-Si3N4 whiskers that are 1-10 mm long and 0.5-1.1 mu m thick were obtained by the reaction of wheat husks with NH3 at 1250-1450 degrees C. A maximum whisker yield of about 30% was obtained at 1450 degrees C with the addition of an iron impurity. Whiskers with 1.3-2.2 mu m thickness (average 1.6 mu m) were obtained by the addition of an H2S impurity. Thin whiskers with periodic thick and thin diameters were also obtained.