"Aneurysm" is a song by the American rock band Nirvana, written by vocalist and guitarist Kurt Cobain, bassist Krist Novoselic, and drummer Dave Grohl.

The song is believed to be about Cobain's relationship with Tobi Vail, of the American punk rock band, Bikini Kill.

Still under contract with Sub Pop, the private session was recorded for free by the band's audio engineer Craig Montgomery, who was friends with Music Source employee Brian Nelson.

"[5] The session tapes were later purchased by DGC, whom the band officially signed with in April 1991, and the two finished songs, "Aneurysm" and "Even in His Youth," were remixed by Andy Wallace and released as b-sides on the "Smells Like Teen Spirit" single in September 1991.

[9] According to the sheet music published at Musicnotes.com by BMG Rights Management, it is written in common time, with a moderately fast rock tempo of 132 beats per minute.

[9] "Aneurysm" is composed in the key of B minor, while Kurt Cobain's vocal range spans one octave and five notes, from a low of A4 to a high of F♯5.

[3] Cross described "Aneurysm" as an attempt to win Vail back, unlike later songs like "Drain You," which instead expressed "his deep level of hurt.

"[2] Reviewing Incesticide for the NME in December 1992, Angela Lewis dismissed the album's side two as "not terribly good" and wrote that "91s ‘Aneurysm’ is lyrically baffling and sounds tired.

"[2] Jenny Pelly of Pitchfork called the song "the apex of [Incesticide] and Nirvana's career," writing that it "never fails to put the stupidest grin on my face, and I cannot hear it without flailing every inch of my body to its squirming emotional upheaval, without jerking my shoulders to its torrential feedback of the heart, as if succumbing to every knot and crevice of this punk song could save my life.

"[17] In 2017, to mark what would have been Cobain's 50th birthday, the Phonographic Performance Limited released a list of the top 20 most played Nirvana songs on television and radio in the UK, in which "Aneurysm" was ranked at number nine.

[18] On April 10, 2014, "Aneurysm" was performed by surviving Nirvana members Grohl, Novoselic and Pat Smear, with lead vocals by Kim Gordon, vocalist and bassist of the American indie rock band Sonic Youth, at Nirvana's Rock and Roll Hall of Fame induction ceremony at Barclays Centre in Brooklyn, New York.

Rolling Stone named it one of the 10 Best Cover Songs of 2014, calling it a "fitting" end to the ceremony given Sonic Youth's role in helping Nirvana attain mainstream success, and writing that "Kurt would've approved.

I sang 'Aneurysm,' with its chorus, 'Beat me out of me,' bringing in all my own rage and hurt from the last few years - a four-minute-long explosion of grief, where I could finally let myself feel the furious sadness of Kurt's death and everything else surrounding it.