软骨硬鳞类是较为原始的辐鳍鱼类，包括古鳕类（Palaeonisciformes）及其近亲、龙鱼（Saurichthys）、多鳍鱼以及鲟类。软骨硬鳞鱼类具有骨质脑颅，但大部分是软骨质组成。上颌骨与前鳃盖骨、下眶骨固结，几乎不能活动。尾鳍为歪型或半歪型。体侧有板质硬鳞。大部分种类已经灭绝，目前仅存多鳍鱼目与鲟形目。

Chondrostei are primarily cartilaginous fish showing some degree of ossification. It is thought that the cartilaginous condition is derived, and that the ancestors of this group were bony fish with fully ossified skeletons. Members of this group share with the Elasmobranchii certain features such as the possession of spiracles, a heterocercal tail and the absence of scales. Nevertheless the fossil record suggests they have more in common with the teleosts. The Chondrostei is probably a paraphyletic grouping; the fifty-two living species are divided among two orders, the Acipenseriformes (sturgeons and paddlefishes), and the Polypteriformes (reedfishes and bichirs).