It is occasionally found as a constituent of nucleic acids, where it is present in the anticodon of tRNA in the form of its nucleoside inosine.

Hypoxanthine is a necessary additive in certain cells, bacteria, and parasite cultures as a substrate and nitrogen source.

In August 2011, a report, based on NASA studies with meteorites found on Earth, was published suggesting hypoxanthine and related organic molecules, including the DNA and RNA components adenine and guanine, may have been formed extraterrestrially in outer space.

[3][4][5] The Pheretima aspergillum worm, used in Chinese medicine preparations, contains hypoxanthine.

Because of its resemblance to guanine, the spontaneous deamination of adenine can lead to an error in DNA transcription/replication, as it base pairs with cytosine.