Black people are far more likely to feel they have been victimised if they are stopped by police, a report shows.
Four in 10 stop-and-search complaints are made by black people
Research revealed black people lodged four out of 10 complaints about stop-and-search powers - despite making up just 2% of the UK population.
And there were flaws in the way use of the powers was recorded, the Police Complaints Authority study added.
PCA chairman Sir Alastair Graham said it proved "not everything was right with the use of the powers".
Of complaints received by the PCA, 44% alleged they had been assaulted by officers during a stop-and-search. A further 25% alleged racism.
Complaints from Asians were also over-represented - they made 8% of complaints but comprise 4% of the population.
Four in 10 complaints about stop-and-search are made by black people
Nearly half of complainants say they have been assaulted by police
A quarter of those who make complaints allege racism
PCA chairman Sir Alastair Graham said stop-and-search was a "highly sensitive issue".
"Black people are much more likely to complain about the use of stop-and-search than they are about other aspects of policing.
"It shows that - given the high volume of activity in stop-and-search powers - that not everything may be right in the use of these powers."
And he added about 11% of complaints received by the organisation were substantiated.
Police forces cut their use of stop and search powers in the wake of the Stephen Lawrence murder report of 1999, amid accusations that some officers disproportionately target black and Asian people.
Use of the powers began to rise again following the 11 September attacks, with police also stopping and searching under anti-terrorism legislation.
The latest available figures show there was a 20% rise in stop and searches in 2001-2002. Stops of black people rose by almost a quarter, by 40% for Asians and by a third for other ethnic groups.
Home Office statistics also show black people are eight times more likely to be stopped and searched than white people - although there are wide regional variations. On average, 13% of those stopped are subsequently arrested for an offence.
Dr David Best, author of the PCA report, said: "Black complainants are four times more likely to make a complaint about stop-and-search than they are to make a complaint about another issue.
"Police recording of stop-and-search was of a wholly unsatisfactory standard.
"The police need to be far better in monitoring fairness and proportionality of stop-and-search."
Most complaints stemmed from the way officers handled the stop-and-search itself, he added.
Of 100 cases analysed by the PCA, 31 officers were referred to the Crown Prosecution Service for consideration of criminal charges against them.
In only one case were charges brought - for indecent assault - but the officer was acquitted at crown court.
A further six officers received advice from a senior officer, one received a reprimand and one a caution.
The PCA is to be replaced by the new Independent Police Complaints Commission.