A report from the European Union Agency for Fundamental Rights found a "large proportion" of healthcare professionals in some EU countries identify being gay as "a pathological problem".
The report said Bulgaria, Hungary, Italy, Latvia, Poland, Romania and Slovakia were among the EU countries where such views were held.
The report, 'Professionally speaking: challenges to achieving equality for LGBT people', also found that the idea that homosexuality is a disease was still present in medical training.
Responding to the findings, Kim Sanders of LGBT charity Stonewall, told The Huffington Post UK: "This research is a reflection of the shocking treatment and inequality that lesbian, gay, bi and trans people face in some European countries.
"Homophobia, biphobia and transphobia underpin these beliefs and they leave the health of LGBT people at severe risk. Not only do LGBT people face abuse and discrimination, they effectively have access to essential healthcare provision blocked because of prejudice."
Report's key findings
In most countries, respondents say there's a lack of objective information about sexual orientation and gender identity in school curricula.
A number of respondents consider homosexual orientation and trans identity to be ‘foreign’ and not in line with the prevailing notion of ‘national identity’.
A lack of awareness, information, data, resources and capacity in respect of the rights of LGBT persons is reinforced by those persons’ "relative invisibility".
There is a need for systematic capacity building, training and awareness raising on the rights and needs of LGBT persons in the areas of education, healthcare and law enforcement.
EU law and policy are drivers supporting efforts to promote LGBT equality, although in several countries respondents claim that policies are not always effectively implemented on the ground.
There can be differences between urban and rural areas in implementing LGBT equality policies.
Sanders continued: "Our own study found 10% of healthcare professionals had heard colleagues express the belief that same-sex attraction could be cured.
"The lack of education, as well as the discriminatory beliefs highlighted in this report and in our research, show how much work there is left for us to do before everyone is treated equally, both in the UK and internationally."
Matthew Hodson of gay men's health charity GMFA, told HuffPost UK: "It’s both shocking and sad that in the 21 century we are still having to argue that homosexuality is not a disease.
"Gay men and lesbians are not disordered and we are not inferior. Our sexuality is not something that needs to be cured."
The report's authors interviewed 1,039 public officials and professionals in 19 EU Member States.
Among the other findings were prevailing negative social attitudes and stereotypes which, the report said, present a major barrier to tackling discrimination and hate crime against LGBT persons.
These affect the actions of public officials, it added.