Amino group-containing organosilicon compounds containing no or only a small fraction of Si-bonded hydroxyl groups are prepared by preparing an organosilicon compound containing amino groups and Si-bonded hydroxyl groups by equilibration in the presence of an equilibration catalyst, and reacting the resultant product with a cyclic silazane. The products are particularly useful as a monomer or macromere for the preparation of high molecular weight organic polymers containing organosilicon blocks.