Abstract: Whiskers having a diameter of 0.1-10 .mu.m and a length of 5-200 .mu.m are pelletized and granulated into agglomerates which have a size of 0.1-10 mm and a bulk density of 0.2-1.0 kg/liter.To pelletize, powders of whiskers are moistened with water while mixing to form primary aggregates. Then, the powders and the primary aggregates are subjected to a rolling movement to cause the primary aggregates to grow into secondary aggregates having desired size distribution. Finally, the secondary aggregates are dried to obtain pelletized or granulated agglomerates of whiskers.Handling of whiskers is facilitated because the agglomerates are less bulky and less likely to fly up in the air. When blended into molding materials for fiber reinforcement, however, the agglomerates are readily disintegrated back into separated individual fibers to provide homogeneous dispersion.