Afghan commanders, former communists, Islamists, women's rights activists and technocrats were sworn in on Monday amid hopes of national reconciliation after decades of war.
Human Rights Watch says up to 60% of the deputies are former commanders or their proxies and the list of deputies reads like a Who's Who of protagonists of the bloody past, boding ill for efforts to account for abuses and to stamp out a drugs trade.
Meanwhile, Taliban spokesmen have vowed more attacks to disrupt "a symbol of American occupation" and warned Afghans to stay away because "agents of foreign infidels" were legitimate targets.
Members of the 249-seat Wolesi Jirga, or lower house, and the 102-member upper house, or Meshrano Jirga, placed their hands on the Quran, the Muslim holy book, and were sworn in by Hamid Karzai, the president.
They swore to respect Islam, the constitution and the law after presidential elections won by US-backed Karzai last year and parliamentary polls in September.
"I thank God that today I am participating in a ceremony that is a step towards rebuilding Afghanistan after decades of fighting"
Former Afghan king
The inauguration was the culmination of a plan to bring democracy to Afghansitan, drawn up after the US-led invasion in 2001 and later backed by the UN.
But many people have been disappointed by the election of factional leaders blamed for rights abuses in polls marred by significant fraud.
Among foreign guests attending the inauguration was Dick Cheney, the US vice-president, who arrived after visiting Washington's more troubled front in Iraq.
Zahir Shah, 91, who was overthrown as king in 1973 by his cousin, Dawud Khan, who dissolved the last parliament, said: "I thank God that today I am participating in a ceremony that is a step towards rebuilding Afghanistan after decades of fighting.
"The people of Afghanistan will succeed!"
Shukria Barakzai, one of two women among more than a dozen candidates bidding to head the lower house, said: "This is a momentous day; I am excited because this is the first parliament we have had after so many decades."
Security was extremely tight after an attacker detonated a car bomb between Nato vehicles near parliament on Friday, killing himself and wounding two passersby.
Roads around the parliament building in western Kabul, refurbished with foreign aid after being damaged in the civil war, were blocked by Afghan troops and Nato-led peacekeepers.
Snipers were in position on rooftops nearby.
Suspected Taliban fighters killed three police officers early on Monday at a frontier post in the eastern province of Kunar, which
Nato-led forces have assisted in
blocking off the parliament area
Moderate MPs and ordinary Afghans have expressed hope that the parliament could mean a more representative government, but it remains unclear how much power it will be able to exercise.
The election was held on an individual not party basis, creating a disparate body expected to have a parochial focus.
Fate of foreign forces
Tens of thousands of US-led foreign troops and billions of dollars of aid is said to have ensured relative stability, and brought new prosperity to cities such as Kabul.
But violence has intensified in the past year and most beneficiaries of the urban boom have been the already rich, while the poor struggle with soaring prices.
There could also be questions raised about the status of foreign troops in the country, with many Afghans feeling that their country should have a say in their activities.