This article offers an overview on the ways and means of the application of Nb in quenched and tempered high-strength steel plates. Thereby, the outstanding role of Nb to control the austenite microstructure during rolling or heat treatment and to contribute to effective precipitation hardening is discussed. It is shown, that Nb is very effective to retard the transformation processes during quenching. For high-strength constructional steels with up to 1100 MPa yield strength and for wear resistant steels, the improvement in strength and toughness properties in Nb microalloyed steels as compared to Nb-free steels is pointed out. A remarkable effect is the improvement in toughness and brittle fracture resistance due to a very fine microstructure and finely dispersed Nb carbonitrides in a martensitic microstructure. Fields of application for the new Nb microalloyed high-strength structural steels are presented too.