Tua was knocked down for the first time in a 56-fight career by a counter-punching Barrett in the final round as he threw caution to the winds in search of a win that would boost his title fight aspirations.
Tua beat the count to see the fight out as, despite the knockdown and a penalty point against him for throwing Barrett to the ground in the 12th round, the judges could not separate the fighters.
One judge had his card 115-112 for Tua while the other two scored it an even 113-113 apiece, meaning Tua retained the WBO Asian Pacific and WBO Oriental heavyweight belts he had staked on a majority draw decision.
Tua, who said he was returning home in the next couple of days, felt the result, although short of what he was looking for, had not damaged his hopes of building up for another title fight.
"It was one of those tough fights that got away -- you just have to look at other things rather than concentrating on just one thing."
Tua said he had thrown Barrett in frustration, but thought he should have just got a warning.
"It was frustrating because the referee had warned him about the way he was grabbing and holding my hands down... and that's why I did it," Tua told NZPA from Atlantic City.
"It (throwing Barrett down) was one of those natural instinctive things and it just came normal... I told the referee the best thing was for him to warn me but that's how it goes sometimes.
"I thought I had done enough to win -- that point they took away was really the defining decision of the fight and that's they way it came out."
The bout at the Tropicana Casino and Resort in Atlantic City exploded in the 12th and final round after neither boxer appeared to have gained the upper hand in the preceding 11.
Tua hit Barrett with a left and a right early in the round but neither had sting. Barrett stayed up and, in frustration as the fighters broke from close contact, Tua wrestled Barrett to the floor, earning the penalty.
Chasing the knockout, Tua then closed in but Barrett responded, launching a series of rights and then a left as he came off the ropes, knocking Tua down.
Barrett, who had previously announced his retirement from the sport after this fight, was shocked by the decision.
"Everybody knows I was the winner. I fought with heart," he said afterwards.
"This is my last fight and I was retiring anyway but this is the sort of thing that makes a man retire, because the sport of boxing is not pure like the fighters."
Tua said he knew he could have done a lot better.
"But it's important not to dwell on it. It's important to look at how we can improve from this performance."
Losing his record of not having been knocked down was not something to regret.
"It was just one of those things -- boxers just got to protect themselves, you know. I'm human being like another man.
"Sometimes you get caught by a good shot and you got to get back up and keep going."
