The NHS should record the ethnicity of all patients to ensure people with mental illness are not discriminated against, a watchdog has said.
A higher proportion of black men are admitted to mental heath hospitals
The Healthcare Commission said some black and ethnic minority groups were three times more likely than average to be admitted to mental health hospitals.
Officials said many factors were behind this but more information was needed to ensure all patients got the best care.
But campaigners said the figures pointed to a "racial divide".
The watchdog also revealed over half of patients were in mixed-sex wards - long regarded as outdated and unsuitable.
The Healthcare Commission's second annual census of mental health patients showed that among some groups hospital admissions were 18 times higher than average.
Rates were lower than average among white British, Indian and Chinese populations, but three times higher for black and white/black mixed groups.
People who listed themselves as in "other black" group, which has a high percentage of second and third generation immigrants, were 14 times more likely than average to be admitted. That figure rose to 18 times more likely among men.
The watchdog did not accuse the NHS of racism, arguing that socio-economic factors meant certain ethnic groups had higher levels of mental illness.
But officials said more information was needed to establish whether the NHS was providing the best care by seeing how patients accessed and used services after a similar pattern had emerged last year.
Only hospital patients have their ethnicity noted at the moment, but the Healthcare Commission said this system should be extended to all NHS services.
The watchdog, in conjunction with the Mental Health Act Commission and National Institute for Mental Health England, gathered information on 32,000 mental health inpatients and 4,600 inpatients with learning disabilities in England and Wales.
The survey also revealed 30% of patients had been in hospital for over a year. Among the black Caribbean group this was as high as 40%.
Professor Sir Ian Kennedy, chairman of the Healthcare Commission, said: "We still need to know more. That is why we are calling for mandatory recording of ethnicity.
"Without this additional information, we cannot effectively monitor the quality of care of black and minority ethnic patients on an ongoing basis."
Paul Farmer, chief executive of the mental health charity Mind, said there was a need for race equality to be built into everything that NHS trusts do.
"These inequalities in mental health care cannot be allowed to continue."
And Kay Hampton, chairman of the Commission for Racial Equality, said the figures were "disgraceful".
"Looking at these figures, we are again reminded of the stark racial divide in this country."
The government said it was considering the report.
And mental health tsar Professor Louis Appleby added: "We know that one size does not fit all, which is why we are determined to ensure that services tailor treatment to meet the needs of different communities and individuals."