The Howard County Office of Human Rights, in a decision believed to be unprecedented in Maryland, has charged that an Elkridge trucking firm violated the county's antidiscrimination law by firing an employe allegedly because he is homosexual.

The office's findings, which are normally confidential, were made public yesterday by a lawyer for Frank W. Rockford, an office manager for Carolina Freight Carriers Inc., who was abruptly fired in 1983 in what the company termed an office reorganization.

The human rights office, however, concluded that Rockford was fired because of his sexual orientation.

A lawyer for the company and a spokesman for the human rights office declined to comment, but gay rights advocates hailed the decision.

"It proves that when you have legal protections based on sexual orientation they can and will be enforced," said Jeff Levi, a spokesman for the National Gay Rights Task Force.

Howard County was the first jurisdiction in Maryland to prohibit discrimination based on sexual orientation.

A hearing on the human rights office's charges will be held by the county's Human Rights Commission, which can assess up to $1,000 in civil penalties against the company. Rockford also could be eligible to collect attorney's fees and up to $30,000 in back pay.