Previous results obtained by different microstructural techniques, including small-angle neutron scattering (SANS), suggested the presence of very small microstructural inhomogeneities in modified martensitic steel DIN 1.4914 (MANET), possibly C Cr elementary aggregates. The present paper reports SANS measurements carried out on MANET samples submitted to various thermal treatments, aiming to check and to extend the previous results and to further characterize the microstructural features of this steel. Significant information is obtained by the analysis of the magnetic and nuclear components of SANS. The size distribution function of the inhomogeneities is also presented and discussed.