Last year's march to the tomb of Imam Musa Kadhim was attacked by mortar bombs, triggering a stampede in which more than 965 people died. It is still the single bloodiest incident in Iraq since the fall of Saddam Hussein.
Security is tight in the capital ahead of Sunday's anniversary march, and the government has announced a vehicle curfew across much of the city centre which will stay in place until after the rally has dispersed.
But, with hundreds of thousands of pilgrims arriving from across the country on foot carrying Shiite banners and Korans, it is proving impossible to protect the entire event.
In the latest violence gunmen shot dead seven pilgrims in the Al-Adel district, and an attacker rammed a Shiite mosque in the Dura neighbourhood in his bomb-laden car, killing one worshipper and wounding four others, a security official said.
One year on from last year's deadly stampede, Baghdad is even more tense than usual.
Daily insurgent bomb attacks target crowds of Shiite civilians, while death squads hunt members of the rival Sunni community. Health officials put the average daily death toll at 50.
Iraqi and US forces have deployed 30,000 troops under an ambitious security plan designed to return order to the war-torn capital, and have had some success in reducing attacks in targeted flashpoint neighbourhoods.
But citywide the violence continues. The mosque bombing was in an area that had been secured last week by a 5,000-strong joint US-Iraqi force.
As part of a security plan for the pilgrimage, the complete ban on vehicles will cover much of central Baghdad near the mosque and the Tigris, Iraq's national police chief Major General Adnan Thabit said.
Pedestrians would be allowed to move within their own districts but pilgrims in the city for their annual march would be limited to two tightly controlled routes across the river, he said.