Teachers have voted to hold a mass boycott of tests for seven, 11 and 14-year-old pupils.
The National Union of Teachers is to ballot its members on action to start this autumn.
The curriculum is suffering, say teachers
It has raised concerns over children's wellbeing, the pressure on staff from exam targets and a narrowing of the curriculum.
After a lively debate at the NUT annual conference in Harrogate, North Yorkshire, members voted unanimously in favour of a boycott.
John Whearty, a secondary school teacher from Liverpool, said the maths and English tests, known as Sats, were "dangerous for our kids".
He added: "It makes me feel quite rotten to be part of something that's so obviously wrong.
"The tests are about collecting useless data, which the government collects and uses to batter teachers.
"These are false measurements, used to determine how well staff are performing.
"The Sats have weighed heavily on us as teachers. It's quite humiliating and it holds us back from other things we should be doing."
'Set up to fail'
After the motion was passed, delegates rose to their feet, repeatedly chanting: "No more Sats."
The NUT, which has 250,000 members, will also circulate a national petition, calling on the Education Secretary, Charles Clarke, to end the tests.
It is planning to hold public meetings, distribute leaflets and approach other unions to join in the boycott.
Sats at age seven are only taken in England, and at age 11 in England and Wales.
Those for 14 year olds are taken in England, Wales and Northern Ireland and include testing on science.
Last year, the Westminster government failed to meet its target that 75% of 11 year olds in England should have reached the required standard in maths and 80% in English.
The NUT claims the pressure to perform in Sats is damaging some children's mental health.
Marilyn Evans, a primary school teacher from Croydon, Surrey, said: "We should stop these Sats. Assessment should be continuous, not in this form. Sats set children up to fail."
John Illingworth, former NUT president, added: "Our most obvious allies are parents. They understand the damage these tests do. We must work with them."
In another debate, the NUT also voted unanimously to condemn the government's handling of school finances.
This came after weeks of complaints that teachers would have to be made redundant because of miscalculations on government funding.
Some schools face six-figure budget deficits as a result of extra payments for pensions, National Insurance and other staffing changes.
A sum of £500m is unaccounted for. The government believes this is being withheld from schools by local authorities.
The authorities claim they have not received the money.
According to the NUT motion, the government has "grossly underestimated" the amount required to make the necessary improvements to education.