前信使RNA（英语：Precursor mRNA，简称为前mRNA）是一种未成熟的单链信使核糖核酸（mRNA）。前mRNA是从细胞核中的DNA模板通过转录而合成的。前mRNA构成了不均一核RNA（或称为核内异质RNA或核内不均一RNA，简称为hnRNA）数量上的主体。hnRNA这一术语通常被用作为前mRNA的同义词，尽管，在严格的意义上说，hnRNA可以包含那些并不最终成为胞浆中mRNA的细胞核RNA转录物。

一旦前信使RNA被完全加工完成，他就被叫做“成熟信使RNA”、“成熟mRNA”或被直接称为“mRNA”。

See main article Primary transcript for more details

Precursor mRNA (pre-mRNA) is an immature single strand of messenger ribonucleic acid (mRNA). Pre-mRNA is synthesized from a DNA template in the cell nucleus by transcription. Pre-mRNA comprises the bulk of heterogeneous nuclear RNA (hnRNA). The term hnRNA is often used as a synonym for pre-mRNA, although, in the strict sense, hnRNA may include nuclear RNA transcripts that do not end up as cytoplasmic mRNA.