The Brazilian mixed martial artist was found unresponsive weeks after completing his sixth fight inside the UFC octagon.
SAO PAULO, Brazil — UFC flyweight Allan Nascimento died Monday at age 34 after he was found unresponsive following an apparent heart attack in his sleep, the mixed martial arts organization announced.
The UFC said emergency medical personnel responded but pronounced Nascimento dead at the scene. The organization described the medical emergency as an apparent heart attack, not a final confirmed cause of death. No additional medical findings or information about where he was found had been publicly released as of Wednesday.
Nascimento’s death came less than seven weeks after his final professional bout. He fought Mitch Raposo on June 20 at UFC Fight Night 279, also promoted as UFC Vegas 119, and lost by split decision after three rounds. The bout left Nascimento with a professional record of 22 victories and seven defeats.
Known by the nickname “Puro Osso,” Nascimento built his career around Brazilian jiu-jitsu and submission grappling. He began competing professionally in 2011 and fought for several organizations before gaining wider attention through Dana White’s Contender Series in 2018.
Nascimento faced Raulian Paiva on the Contender Series and lost a close split decision. Although the appearance did not immediately earn him a UFC contract, he later joined the promotion and made his octagon debut against Tagir Ulanbekov at UFC 267 in October 2021.
He finished his UFC career with four wins and two losses. His victories included decisions over Jake Hadley and Jafel Filho and submission wins against Carlos Hernandez and Cody Durden. Nascimento’s November 2025 victory over Durden came by anaconda choke in the second round.
Nascimento trained with the Chute Boxe Diego Lima team in Sao Paulo, a gym associated with several prominent Brazilian mixed martial artists. His fighting style reflected his long background in grappling, with most of his professional victories coming through submissions or decisions rather than knockouts.
The UFC announced his death in a statement expressing condolences to his family, friends, teammates and loved ones. Fighters and other members of the mixed martial arts community also shared tributes following the announcement, remembering Nascimento as a respected teammate and competitor.
Nascimento had remained active in the flyweight division before his death. He returned to competition in 2025 after a lengthy absence and earned three consecutive victories before the June loss to Raposo. That bout was his first professional defeat since his UFC debut nearly five years earlier.
The organization had not announced plans for a formal memorial as of Wednesday. Further information about the medical circumstances surrounding Nascimento’s death had not been released.
Author note: Last updated August 5, 2026.