[1] Ireneo "Rene" Barrientos was born on July 25, 1943, in Balete, Aklan, the fourth of 10 children whose father was a policeman.
Like most boxers, Barrientos dropped out of school at age 17 due to poverty and worked as a mechanic's helper in a logging firm.
He transferred to Cagayan de Oro and on February 27, 1965, he faced his idol Flash Elorde in a 12-round match for the Orient Pacific Boxing Federation lightweight title at the Cebu Coliseum.
[2] After 11 straight victories following the match with Elorde, he lost a decision then draw the rematch in succession with future junior welterweight champion Pedro Adigue Jr. on January 21 then on February 17, 1967.
On April 29, 1967, he won the Philippine super featherweight title via points decision over Raymond Rivera in a fight held in Davao City.
But he returned to the ring in 1978 for two more victories in fights against Filipino Joe Faune by 2nd-round KO and Thai Jong Satherigym by decision.