The number of gay hate crimes being reported to police in Devon and Cornwall has fallen by about 30% over the last five years, the force says.
There were 135 crimes reported in the year ending March 2005, compared to 94 during the same period in 2009.
The Intercom Trust in Exeter - which supports local lesbian, gay, bisexual and transgender people - said many cases were still remaining unreported.
Police said they were working to encourage more victims to come forward.
Andy Hunt, from the Intercom Trust, said he often dealt with people who did not feel there was any point in reporting incidents of harassment or discrimination.
He said: "We do work with people to try and encourage them to report things to the police.
"But some people think they won't take it seriously. There is a lack of trust and confidence in the authorities."
Diversity officer Sgt Glynn Currey said the force had come a long way in dealing with such crimes.
But he added that officers understood why victims were reluctant to come forward.
He said: "People will have had negative experiences with us in years gone by, or with another force. We are aware of that.
"We now put in a large amount of effort to ensure people are safe and they can come to us in confidence with their concerns."