DNA matches from the national database help solve as few as one crime in every 1,300, it was claimed today.
Figures published in a Home Affairs Select Committee report suggest just 3,666 crimes are detected every year with links to an existing DNA profile.
That is one in every 1,300 of the 4.9 million crimes carried out, and just one in 350 of the 1.3 million crimes solved by police.
In their report, the MPs called for innocent people's DNA to be held on the database for only three years after it is taken, instead of the six years proposed by ministers.
Currently genetic profiles from anyone arrested but later released without charge or cleared in court are held indefinitely.
But under proposed laws currently going through Parliament they will be held for up to six years before being deleted, except in terrorism cases.
Senior police officers told the committee that around 33,000 crimes are solved using DNA matches.
But many of those would be solved even without the need for a national database, the report said.
It quotes the 3,666 figure, which was calculated by Genewatch, a pressure group, but warns it is difficult to be sure the figure is accurate.
The report states: "It is currently impossible to say with certainty how many crimes are detected, let alone how many result in convictions, due at least in part to the matching of crime scene DNA to a personal profile already on the database, but it appears it may be as little as 0.3%."
Committee chairman Keith Vaz said: "DNA profiling and matching are vital tools in the fight against crime.
"However, especially in the case of those who are arrested and have their DNA taken but are then never charged, or never convicted of a crime, it is a very complex issue to balance the potential benefit of retaining their data against the threat to individual privacy.
"We do not think we should go back to the situation where DNA is only taken on charge, not arrest, but it is vital that it is made easier for those wrongly arrested or who have volunteered their DNA to get their records removed from the database.
The report said there was a "lack of consistency" in decisions on whether to remove the DNA of innocent people.
Mr Vaz called for a "consistent, fair and prompt" central system to replace individual decisions made by individual Chief Constables.
Critics have claimed there is a "postcode lottery" for decisions, with some forces refusing to remove any records once a case is closed while others deleted in 80% of request cases.
The MPs said their inquiry was launched amid "growing public concern" over the size of the database, which now holds the profiles of more than 5.5 million people.
A Home Office spokesman said: "We are pleased that the committee agrees with the Government that the DNA database is a vital tool for protecting the public and bringing offenders to justice, and that retaining profiles is a crucial aspect of that.
"Retaining profiles on the database helps provide thousands of crime scene matches every year, especially in the detection of many violent and serious acquisitive crimes where physical contact occurs.
"We therefore believe that the proposals currently before Parliament represent the most proportionate approach to DNA retention, as well as the most effective way of ensuring the database continues to help us tackle crime."
Liberal Democrat home affairs spokesman Chris Huhne said: "The clear line between innocence and guilt has been blurred by Labour for too long.
"People who have committed no crime should be removed from the largest DNA database in the world.
"The Liberal Democrats have tabled amendments to today's Bill to make that happen."
Isabella Sankey, policy director of civil rights group Liberty, said: "Everyone knows that DNA can be incredibly useful in convicting the guilty and clearing the innocent but as these figures show, DNA evidence is no silver bullet in the fight against crime.
"Our current retention regime is unlawful and the Government's half-baked proposals are little better. Parliamentarians must now aim to create a smarter DNA database - one that stores the details of dangerous offenders but not every man, woman and child who has ever been arrested."