A fight between rival gangs sparked Monday's fire - the deadliest incident in the history of the country's prisons.
Efforts to rescue the prisoners from the blaze in the eastern city of Higuey were hampered by a broken lock, officials said.
By midday, 133 bodies had been counted and about 25 people were injured, said a spokeswoman for the Civil Defence Department.
Rival gangs fighting for control of the prison attacked each other with guns and knives late on Sunday, officials said.
The blaze broke out early on Monday as prisoners set fire to
Prison guards said they tried to open the cellblock where the fire was raging but prisoners had damaged the lock, prisons director Juan Ramon De la Cruz Martinez said.
Rescue workers were still bringing out bodies from the prison at noon. Dozens of people gathered nearby, hoping for news of their relatives.
Police chief Manuel de Jesus Perez Sanchez ordered the arrest of the prison's security chief.
The Dominican Republic's prisons are often overcrowded. Twenty-nine inmates were killed in a riot and fire at a prison in the city of La Vega in September 2002.
The US State Department, which issued its annual report on human rights around the world last week, said prison conditions in the Dominican Republic range from "poor to harsh".
"[Prison conditions in the Dominican Republic range from] poor to harsh"
US State Department report
It said prisons were seriously overcrowded and sometimes out of the control of the authorities, in effect operated by armed inmates.
Journalists said the prison at Higuey was built in 1960 and often held up to 400 people, more than double its supposed capacity.
The Dominican Republic has a population of nearly 9 million and shares the island of Hispaniola with Haiti.