Campaigners claim there are more restrictions on gay people
A petition by gay rights campaigners against what they believe is discrimination over who can give blood is to be considered by MSPs.
The LGBT Network said safe sex practices meant men who have sex with other men should be able to give blood.
The group pointed out that there were no restrictions on heterosexual people who have unprotected sex giving blood.
The Scottish National Blood Transfusion Service said it had a duty to make sure patients got the safest blood possible.
A spokesman for the LGBT (Lesbian, Gay, Bisexual and Transgender) Network said: "The blanket ban on gay and bisexual men giving blood is an outdated policy that was put in place decades ago when people believed Aids was an exclusively gay disease.
"We now know that this is far from the case. There is no clinical reason for the blanket ban on gay and bisexual men giving blood.
"It is a policy from a bygone era, which unfairly discriminates.
Campaigner explains why he wants to give blood
"The SNBTS should instead focus on all donors' unsafe sexual practices, rather than single out gay and bisexual men."
But Dr Brian McClelland, from the Scottish Blood Service, said: "Even the highly sensitive tests for hepatitis and HIV that are performed on every donation cannot completely exclude all risk of infection, so an essential first step - and a requirement of UK law - is to avoid collecting donations if there is evidence that the risk of blood-transmissible infections may be raised.
"The blood services of the UK, like those in most European countries, USA and Canada, do not accept donations from men who report that they have had sex with another man.
"Over 60% of all the HIV diagnoses where the infection was likely to have been acquired in the UK were in gay men.
"Other infections that are sexually transmitted and also transmitted by blood, such as hepatitis B and syphilis, are also increasing among men who have sex with men. Syphilis increased 117% from 2002 to 2006."
Dr McClelland said research continued to show that removing the current bar on donations by men who have sex with men would lead to an increase in the very small risk of HIV transmission due to infections in the very early stage that may be impossible to detect.
The issues were examined by the Scottish Parliament's petition committee on Tuesday.
Tory committee member Nanette Milne said she was a former blood donor who could no longer donate because of medication she was taking.
"The paramount thing has to be public safety as far as possible when dealing with blood donations," she said.
"I think there are very serious issues within this and I understand why the blood transfusion service has the rules and regulations it has at the present time."
The committee agreed to write to the Scottish Government, blood and tissue organisations, as well as pressure groups on the issue for further information.
A Scottish Government spokeswoman said ministers realised the rule that excludes gay and bisexual male donors was "frustrating" for people who felt they carried no risk.
But she added: "It is sometimes necessary to exclude people whose blood would probably be safe because they are from part of a group that carries a high risk.
"Advances in blood transfusion safety procedures may allow gay and bisexual male donors to donate in the future."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.