The jawbone is human, though it is unclear who it belongs to.
Dutch investigators compared the lone tooth on the bone with dental records supplied by Holloway's family and "it can be ruled out that the bone fragment came from Natalee Holloway," the prosecutors said.
The bone was found recently by a tourist on a beach, and Aruba prosecutors had asked forensic scientists in the Netherlands to analyze it.
They assured that the Holloway case has "the constant attention from law enforcement on the island."
The announcement once again eliminates a hope of evidence about the fate of the Mountain Brook, Alabama, student who disappeared while on a high school graduation trip in 2005, when she was 18.
Aruba's attorney general, Taco Stein, told The Associated Press that officials do not know how old the bone is or where it might have come from.
"It's anybody's guess," he said. "We're a small island."
He speculated that it could even have come from nearby Venezuela or Curacao, given the intense hurricane season that churned the ocean.
Stein said authorities will check with police to see if the jawbone might belong to a missing person or the victim of an unsolved murder, but he said it was unlikely because Aruba only has a handful of those types of cases.
Holloway's parents, Dave Holloway and Beth Twitty, did not respond to calls for comment.
Family attorney Vinda de Sousa told The Associated Press that the family might issue a statement later.
Earlier in the day, Carol Standifer, who said she is a close friend of the teen's mother, told CBS's "The Early Show" that if the bone did belong to the missing teen, "there will be some semblance of closure."
Holloway was last seen leaving a bar with Dutchman Joran van der Sloot, the prime suspect in her disappearance, on the final night of her trip.
Aruba prosecutors have repeatedly said they lack evidence to charge Van der Sloot, who is in jail in Peru on charges of killing a 21-year-old woman last May 30 - five years to the day after Holloway's disappearance. He has denied killing Holloway.
U.S. law enforcement officials have charged Van der Sloot with trying to extort money from Holloway's mother to reveal the location of Holloway's body.
