Various hyperbranched polymers with alternating ureido and urethano units in theirbackbones were synthesized by direct polycondensation of diisocyanates (A2-type monomers) withcompounds containing one amino group and multihydroxyl groups (CBn-type monomers). Because of thecommercial availability of the monomers and the simplicity of the synthesis process, hyperbranched poly(urea−urethane) materials can be large scale accessed. The reaction between an A group and a C groupis much faster than that between an A group and a B group, resulting in the formation of ABn-typeintermediates in the initial stage of the reaction. Further self-polycondensation of the intermediates giveshyperbranched macromolecules. The influence of reaction conditions such as temperature and concentration on the polymerization was discussed in detail.