The influence of polydispersity on liquid-crystalline ordering in anisotropic polymer brushes is considered. It is shown that mixing of long and short chains in a brush inhibits LC ordering of long chains; LC ordering is influenced by details of the inner structure of a brush rather than by its global average characteristics. There exists a regime of LC ordering in which the transition point is governed by the length of the short chains and the overall grafting density only, independent of the brush content. After LC ordering of the short chains is finalized, the ordering of long chains may proceed as a second-order phase transition.