杂交探针（英语：Hybridization probe）是一小段单链DNA片段（十几到几百个碱基），用于检测与其互补的核酸串行。双链DNA加热变性成为单链，随后用放射性同位素（通常用P）、萤光染料或者酶（如辣根过氧化物酶）标记成为探针。P通常被掺入组成DNA的四种核苷酸之一的磷酸基团中，而荧光染料和酶与核酸串行以共价键相连。

当将探针与样品杂交时，探针和与其互补的核酸（DNA或RNA）串行通过氢键紧密相连，随后，未被杂交的多余探针被洗去。最后，根据探针的种类，可进行放射自显影、萤光显微镜、酶联放大等方法来判断样品中是否含有，或者何位置含有被测串行（即与探针互补的串行）。

In molecular biology, a hybridization probe is a fragment of DNA or RNA of variable length (usually 100-1000 bases long) which can be radioactively labeled. It can then be used in DNA or RNA samples to detect the presence of nucleotide sequences (the DNA target) that are complementary to the sequence in the probe. The probe thereby hybridizes to single-stranded nucleic acid (DNA or RNA) whose base sequence allows probe-target base pairing due to complementarity between the probe and target. The labeled probe is first denatured (by heating or under alkaline conditions such as exposure to sodium hydroxide) into single stranded DNA (ssDNA) and then hybridized to the target ssDNA (Southern blotting) or RNA (Northern blotting) immobilized on a membrane or in situ.