遗传学上的重组是指DNA片段断裂并且转移位置的现象，也称为遗传重组或是基因重组。发生在减数分裂时非姐妹染色单体上的基因结合。

对原核生物（例如细菌）来说，个体之间可以透过交接，或是经由病毒（例如噬菌体）的发送，来交换彼此的基因，并且利用基因重组将这些基因组合到本身原有的遗传物质中。

对于较复杂的生物来说，重组通常是因为同源染色体配对时发生互换，使得同源染色体上的基因在遗传到子代时，经常有不完全的连锁。由于重组现象的存在，科学家可以利用重组率来定出基因之间的相对位置，描绘出基因图谱。

Genetic recombination is the production of offspring with combinations of traits that differ from those found in either parent. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on from the parents to the offspring. Most recombination is naturally occurring. During meiosis in eukaryotes, genetic recombination involves the pairing of homologous chromosomes. This may be followed by information exchange between the chromosomes. The information exchange may occur without physical exchange (a section of genetic material is copied from one chromosome to another, without the donating chromosome being changed) (see SDSA pathway in Figure); or by the breaking and rejoining of DNA strands, which forms new molecules of DNA (see DHJ pathway in Figure). Recombination may also occur during mitosis in eukaryotes where it ordinarily involves the two sister chromosomes formed after chromosomal replication. In this case, new combinations of alleles are not produced since the sister chromosomes are usually identical. In meiosis and mitosis, recombination occurs between similar molecules of DNA (homologs). In meiosis, non-sister homologous chromosomes pair with each other so that recombination characteristically occurs between non-sister homologues. In both meiotic and mitotic cells, recombination between homologous chromosomes is a common mechanism used in DNA repair.