At least 30 people have been killed by a suicide bomber in Talafar, police said, in the second major attack on the northern Iraqi town in as many days.
The latest attack killed recruits who had gathered for work at an army base.
In Tuesday's attack, up to 30 people were killed in a suicide bombing at a crowded marketplace in Talafar.
Iraqi leaders are meanwhile set to consider last-minute changes to the draft constitution that could overcome Sunni Arab objections to the document.
Iraqis go to the polls on Saturday to vote on the constitution.
Sunni leaders have said they fear the current proposals would lead the country to split into a Kurdish north and Shia south, depriving them of access to the country's oil resources.
But following talks with Shia and Kurdish leaders, one of the main Sunni parties has said it will endorse the constitution if the new parliament, to be elected in December, is allowed to amend the text.
Iraqi officials say the parliamentary session due to take place late on Wednesday will ratify changes already agreed on Tuesday night.
Police said at least 35 people were injured in Wednesday's blast at Talafar, which targeted a recruiting centre at about 1000 (0700GMT).
"About 500 people were waiting outside the centre when the suicide bomber blew up his explosives belt," said Talafar police chief General Najim Abdullah.
Correspondents say such attacks raise the question of whether residents of western Iraq will be able to vote safely in Saturday's referendum.
Talafar, about 150km (90 miles) from the Syrian border, is a centre for Iraqi insurgents and thought to be a staging-post for foreign fighters.
Last month, US and Iraqi claimed to have killed 200 insurgents and driven out many more in an assault on the town.