即时聚合酶链锁反应（Real-time polymerase chain reaction，简称 Real-time PCR、即时PCR），又称定量即时聚合酶链锁反应（Quantitative real time polymerase chain reaction，简称 Q-PCR/qPCR/qrt-PCR、定量即时PCR、即时定量PCR），是一种在DNA扩增反应中，以萤光染剂侦测每次聚合酶链锁反应（PCR）循环后产物总量的方法。

定量即时PCR及定量反转录PCR（quantitative reverse transcription PCR, qRT-PCR）已被众多科学家采用，因为其侦测范围广、灵敏度高、准确、专一及快速。qPCR的发展因为侦测感染病患的病毒或细菌量、癌症监测、诊断个别基因差异的用药反应等应用而大幅提高。

A real-time polymerase chain reaction is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR, i.e. in real-time, and not at its end, as in conventional PCR. Real-time PCR can be used quantitatively (Quantitative real-time PCR), semi-quantitatively, i.e. above/below a certain amount of DNA molecules (Semi quantitative real-time PCR) or qualitatively (Qualitative real-time PCR).