BBC
Newt Gingrich, the new frontrunner, fought off heavy attacks from rivals who portrayed him as a Washington insider and questioned his judgement.
Meanwhile, correspondents say Mitt Romney may have hurt his campaign by challenging fellow contender Rick Perry to a $10,000 (£6,300) bet.
The debate is the 12th since the campaign began.
In January, Iowa will hold the first in a series of state-by-state contests that will help pick the party's candidate to challenge Democratic President Barack Obama for the White House in November 2012.
Big bet
In the opening minutes of the debate, Mr Romney, a former Massachusetts governor, set out why he could bring the US economy back from the brink.
"We don't need folks who are lifetime Washington people," Mr Romney said
But Mr Romney found himself under attack too, with the governor of Texas, Rick Perry, arguing against the former's healthcare policies.
Mr Romney also offered up a $10,000 bet over healthcare - a move which some say will portray him as out of touch with the public, especially at such a time of economic hardship.
Meanwhile, Mr Gingrich defended his recent statement that the Palestinians were an "invented" people.
"Is what I said factually true? Yes," Mr Gingrich said. "Somebody ought to have the courage to tell the truth. These people are terrorists."
His remarks drew an angry response from Palestinian officials.
Palestinian Prime Minister Salam Fayyad said Mr Gingrich's comments "constituted a totally unacceptable distortion of historical truth", calling them "vulgar, hurtful and ridiculous".
The debate is also the first since Herman Cain left the race after allegations of sexual harassment and an extra-marital affair.
Mitt Romney offers up a $10,000 bet to Rick Perry - Clip courtesy ABC News
Republican presidential hopefuls have taken part in a televised debate in the US state of Iowa.
Meanwhile, correspondents say Mitt Romney may have hurt his campaign by challenging fellow contender Rick Perry to a $10,000 (£6,300) bet.
The debate is the 12th since the campaign began.
In January, Iowa will hold the first in a series of state-by-state contests that will help pick the party's candidate to challenge Democratic President Barack Obama for the White House in November 2012.
Big bet
In the opening minutes of the debate, Mr Romney, a former Massachusetts governor, set out why he could bring the US economy back from the brink.
"We don't need folks who are lifetime Washington people," Mr Romney said
But Mr Romney found himself under attack too, with the governor of Texas, Rick Perry, arguing against the former's healthcare policies.
Mr Romney also offered up a $10,000 bet over healthcare - a move which some say will portray him as out of touch with the public, especially at such a time of economic hardship.
Meanwhile, Mr Gingrich defended his recent statement that the Palestinians were an "invented" people.
"Is what I said factually true? Yes," Mr Gingrich said. "Somebody ought to have the courage to tell the truth. These people are terrorists."
His remarks drew an angry response from Palestinian officials.
Palestinian Prime Minister Salam Fayyad said Mr Gingrich's comments "constituted a totally unacceptable distortion of historical truth", calling them "vulgar, hurtful and ridiculous".
The debate is also the first since Herman Cain left the race after allegations of sexual harassment and an extra-marital affair.
Comments