UFC Flyweight Allan Nascimento Dies at 34 After Apparent Heart Attack in His Sleep

UFC flyweight Allan Nascimento died Monday, August 3, after suffering an apparent heart attack in his sleep, the promotion announced. He was 34.

According to a UFC statement, Nascimento was found unresponsive at home that morning. Emergency medical responders attempted to revive him but he was pronounced dead at the scene.

"This morning, Monday, August 3, our beloved fighter and exemplary flyweight Allan Nascimento was found unresponsive after suffering an apparent heart attack in his sleep," the UFC said, according to The Guardian. "Despite the efforts of the responding medical team, he was pronounced deceased at the scene. Our thoughts and deepest condolences are with Allan's family, friends, teammates, and loved ones during this incredibly difficult time."

Nascimento, nicknamed "Puro Osso" (Portuguese for "All Bones," a nod to his lean frame), was a Brazilian fighter representing the Chute Boxe Diego Lima team out of São Paulo. He turned pro in MMA in 2011 and built a 22-7 career record, according to UFC.com and ESPN.

He made his promotional debut on Dana White's Contender Series in 2018, dropping a split decision to Raulian Paiva. That performance was strong enough to land him a UFC contract in 2021, according to Bleacher Report.

Over six UFC appearances, Nascimento went 4-2, with wins over Cody Durden, Jafel Filho, Carlos Hernandez, and Jake Hadley. He lost to Tagir Ulanbekov and, most recently, to Mitch Raposo on a split decision in Las Vegas on June 20. He earned two Performance of the Night bonuses during his UFC run.

Nascimento trained alongside former UFC lightweight champion and current BMF titleholder Charles Oliveira, a teammate who paid tribute following news of his death.

"Today I lost a brother I gained through the fight game," Oliveira said, according to The Nightly. "Thanks for always being there, for sharing the mats and the grind, and for your words. I'm so grateful to have had you by my side, brother, through training, the tough times, and the good times hanging out. Love you, man, you're a legend."

The Nightly reported that tributes have also come in from Dustin Poirier, Henry Cejudo, and Mackenzie Dern as word of Nascimento's death spread through the mixed martial arts community.

UFC.com's own memorial noted that 16 of Nascimento's 22 career wins came by submission, and that he was "a fixture on the doorstep of the Top 15" in the flyweight rankings, describing him as sharing an especially close bond with Oliveira.

No cause of death beyond "apparent heart attack" has been specified by the UFC or by any medical examiner in the available statements. No autopsy findings have been reported publicly as of this writing, and no investigation has been announced.

Daily Wire's coverage noted that heart attacks are typically associated with older adults, citing what it described as a broader rise in cardiovascular events among younger people in recent years. That claim is presented generally, without a specific study or medical source named in connection with Nascimento's case, and no source has offered a specific medical explanation for his death.

Nascimento's death adds to a grim recent stretch for combat sports, which has seen several young fighters die suddenly in the last few years, though no pattern specific to Nascimento's case has been established by any medical authority in the reporting so far.

The fighter's last bout was less than seven weeks before his death. Whether Brazilian or Nevada medical authorities will release further details on the cause of death remains an open question, as none of the available UFC or media statements reference an autopsy or toxicology report.