South Carolina Republican Rep. Joe Wilson shouted "You lie!" after Obama had talked about illegal immigrants.
It wasn't the only interruption during Obama's speech to a joint session of Congress in the House of Representatives. Earlier, Republicans laughed when Obama acknowledged that there are still significant details to be worked out before a health care overhaul can be passed.
Wilson's outburst caused Obama to pause briefly before he went on with his speech. Overhead in the visitors' gallery, first Lady Michelle Obama shook her head from side to side.