Allan Nascimento, the Brazilian UFC flyweight nicknamed Puro Osso, Portuguese for "All Bones," for how lean he was as a teenager, was found unresponsive on Monday morning August 3 after suffering an apparent heart attack in his sleep.
A responding medical team attempted to revive him and was unsuccessful. He was pronounced dead at the scene. He was 34 years old. He is survived by his wife and two children.
"This morning, Monday, August 3rd, our beloved fighter and exemplary flyweight, Allan Nascimento, was found unresponsive after suffering an apparent heart attack in his sleep," the UFC said. "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 went 22-7 as a professional and 4-2 inside the UFC after signing with the promotion in 2021. Fifteen of his 22 career victories came by submission, he was trained at the renowned Chute Boxe Diego Lima gym alongside former UFC lightweight champion Charles Oliveira.
He won four straight UFC bouts from 2022 to 2025, earning two Performance of the Night bonuses. His final fight was a split decision loss to Mitch Raposo on June 20, 2026, six weeks before he died.