* Joe Wilson's fellow Republicans rally to his side

* Democrats say action needed to defend House decorum

(Adds details, background)

WASHINGTON, Sept 15 (Reuters) - The Democratic-led U.S. House of Representatives on Tuesday reprimanded the Republican lawmaker who yelled "You lie!" at President Barack Obama during Obama's speech to Congress last week on healthcare reform.

On a largely party-line vote of 240-179, the House passed a resolution of disapproval against Joe Wilson, who was a relatively obscure congressman from South Carolina until his outburst during Obama's nationally broadcast address.

A resolution of disapproval is the lowest form of punishment in the House and carries no penalty other than being cited for a breach of the chamber's rules of conduct.

Obama's push to reform the $2.5 trillion U.S. healthcare industry has also split Congress largely along party lines. [ID:nN1579678]

"None of us is happy to be here considering the resolution before us. I know I am not," House Democratic Leader Steny Hoyer told colleagues in a speech before the vote.

"What is at issue here is of importance to this House and to our country. And that issue is whether we are able to proceed with a degree of civility and decorum that our rules and our democracy contemplate and require."

House Republicans rallied to Wilson's side and opposed the resolution. During the vote, many patted him on the back and shook his hand.

They agreed that Wilson had made a mistake in shouting at Obama. But they noted the congressman had promptly apologized to the president in a telephone call to the White House and that Obama had accepted the apology.

Wilson rejected calls by Democrats as well as some Republicans to offer a separate apology in the House.

"It is clear that there are far more important issues facing this nation," Wilson said in a speech before the vote. "It is time to get on with the work of the American people."

While the five-term lawmaker from South Carolina has been widely scorned, he also has emerged as a hero among some conservatives.

Wilson and his Democratic challenger in next year's congressional election, Rob Miller, each claim to have raked in more than $1.5 million in campaign contributions since the Wilson yelled at Obama.

A USA Today/Gallup Poll released on Tuesday found that 68 percent of respondents said they oppose what Wilson did, while 21 percent said they support it. (Additional reporting by Andy Sullivan and John Whitesides; Editing by John O'Callaghan and Bill Trott)