1. Small grained maraging steel has a higher ductility than the large grained steel but in a number of cases the influence of the grain size is masked by other singularities of the steel. 2. Extracted carbon replicas of the surfaces of the fractures of steel samples with the highest ductility are free from intermetallic and nonmetallic inclusions. 3. The replicas from fractures of steel samples of low ductivity contain particles of ZrN and Ti2S extracted from the matrix. Slow cooling from the rolling temperature is responsible for the formation of thin films consisting of particles of titanium carbides and titanium nitrides along the boundaries of austenite grains.