微小核糖核酸病毒科（Picornaviridae）是没有套膜、正股RNA、正20面体蛋白壳体的病毒，它的基因体在5'端有一个蛋白是用来当作RNA复制的primer，它的命名pico代表小，rna代表着核糖核酸，故Picornavirus的意思即微小的RNA病毒。微小病毒科根据巴尔的摩分类法归类为第四纲，基因体大小从7.2kb至9.0kb。微小病毒科的mRNA在5'端并没有CAP而是一种蛋白质称为VPg，3'端一样具有poly A tail，基因体两端均有UTR（un-translated region，非转译区）。
微小病毒科可分为九属，最常见的为肠病毒属（Enteroviruses）及鼻病毒属（Rhinoviruses）。肠病毒主要感染消化系统，可以忍耐低pH值的环境；鼻病毒则感染呼吸道。常见的病源体还有肠病毒70型、克沙奇病毒、A型肝炎、手足口病病毒等。

A picornavirus is a virus belonging to the family Picornaviridae. Picornaviridae is a family of viruses in the order Picornavirales. Vertebrates, including humans, serve as natural hosts. There are currently 50 species in this family, divided among 29 genera. Diseases associated with this family include: paralysis (non-polio and polio-type), summer cold, meningitis, diarrhea caused by Enteroviruses; foot-and-mouth disease (bovine) caused by Aphthoviruses; myocarditis caused by Cardioviruses; common cold caused by Rhinoviruses; and hepatitis caused by Hepatoviruses. The name is derived from pico, meaning "small," and RNA, referring to the ribonucleic acid genome. Thus, "pico-rna-virus" literally means "small RNA virus."