The first bomb rocked a minibus pulling into a busy square in the Shiite neighborhood of Sadr City in Baghdad, killing four people and wounding 11 others, said a police official.
The driver, who refused to give his name, said his minibus was full of pilgrims returning from the Shiite holy city of Karbala, 50 miles south of the capital.
The second minibus, also coming from Karbala, was hit in the Shiite neighborhood of al-Kamaliya in southeast Baghdad. That blast killed four people and wounded 13 others, the police official said.
Medical officials confirmed the number of dead and wounded in the two attacks. All the officials spoke on condition of anonymity because they were not authorized to talk to the media.
The attacks followed a series of bombings last week targeting pilgrims on their way to Karbala that killed 60 people.
Hundreds of thousands of Shiite pilgrims converged on Karbala in recent days to celebrate the end of 40 days of mourning that follow the anniversary of the seventh-century death of one of Shiite Islam's most revered saints, the Prophet Muhammad's grandson Hussein.
Most of the pilgrims left Karbala early on Monday after the end of the religious ceremony, and the Iraqi government called on owners of private vehicles to help ferry them home.
The Iraqi government deployed more than 30,000 security personnel to protect the pilgrims, but the long distances that many Shiites travel to Karbala make it difficult to shield them from all attacks along the way.
Sunni militants have kept up their attacks against Shiites, hoping to re-ignite the kind of sectarian violence that engulfed the country two years ago.
But the Iraqi government has also stepped up its offensive against extremists throughout the country.
Iraqi Prime Minister Nouri al-Maliki launched several operations against Sunni and Shiite militants last year, including one in the northern city of Mosul, where a roadside bomb targeting an Iraqi army patrol killed one soldier Monday, said police.
The operations have helped reduce violence in Iraq to a five-year low and propelled al-Maliki's party to victory in provincial elections held throughout much of the country on Jan. 31.
Iraqi election officials plan to announce final results this week. But preliminary figures announced Feb. 5 indicate al-Maliki's ticket beat Shiite religious parties in Baghdad and southern Iraq, including its main rival, the Supreme Islamic Iraqi Council, which has close ties to Iran.
The Supreme Council won control of much of the south in the last provincial elections in 2005.
Humam Hammoudi, a senior member of the Supreme Council, said his party has set up a committee to look into the "surprise" results from the recent provincial elections.
"The way the election results turned out contradicted the forecasts and expectations," Hammoudi said in an interview published Monday in the pan-Arab Al-Hayat newspaper.
The Supreme Council has lobbied to carve out a semiautonomous region in the oil-rich south similar to the Kurdish-ruled area in the north an idea that al-Maliki has strongly opposed.
Another area where there has been controversy relates to certificates candidates needed to verify that they had at least a high school diploma so they can run.
Abdul-Aziz al-Hakim, the head of the Supreme Council, criticized the election commission and demanded the group address cases of fraud before announcing final results.
"The results of the provincial elections were not accurate," U.S.-funded Radio Sawa quoted al-Hakim's son and heir apparent, Ammar, as saying in a speech delivered on behalf of his ailing father Sunday in Karbala.
The results "indicate fraud by influential parties in the election commission," he was quoted as saying.