WATCH: This Man's Doctor Diagnosed Him a 'Chronic Homosexual'

When Matthew Moore began seeing a new doctor in Manhattan Beach, Calif., he didn't object to a routine physical exam to establish care. But when the openly gay man reviewed his treatment plan, he noticed something odd.

In addition to listing what he says are "normal" chronic issues for him, like high blood pressure, cholesterol, and a B-12 deficiency, his doctor had also listed "homosexual behavior" as a "chronic condition." Next to the diagnosis was medical reference code 320.0, a classification that lists homosexuality as a disease -- a designation that hasn't been used since homosexuality was removed from the list of mental illnesses in 1973.

"My jaw was on the floor," Moore told Southern California's NBC4. "At first, I kind of laughed, I thought, 'here's another way that gay people are lessened and made to feel less-than,' and then as I thought about it and as I dealt with it, it angered me."

Moore told NBC4 that when he later returned to the office to challenge his doctor's diagnosis, the doctor stood by her claims. Moore says the doctor told him that a treatment for homosexuality "is still up to debate," and that a gay sexual orientation is "still thought of as being a disease."

Moore told NBC4 he doesn't mind that his chart notes that he's openly gay, but he takes issue with his sexual orientation being categorized as a chronic health condition.

Displeased with his doctor's response, Moore filed a complaint with the Torrance Health Association, which runs the doctor's office he visited. Moore demanded the company return his $30 copay -- which the company did, along with a letter apologizing.

"We would like to unequivocally state that the Torrance Memorial Physician Network does not view homosexuality as a disease or a chronic condition and we do not endorse or approve of the use of Code 302.0 as a diagnosis for homosexuality," wrote senior director of Torrance Health Association Heidi Assigal in the company's response. "We fully appreciate your frustration and anger related to your experience and are committed to ensuring that such events are not repeated."

Moore told NBC4 that he's satisfied with the company's response, and asked that the doctor's name be withheld to protect her reputation. But he wants to share his story to let others know it's OK to speak up.

"If I was a 14-year-old in a small town in Indiana, where I'm from, and I had a doctor tell me or my parents that I was sick because they thought I was gay, it would've been very damaging," Moore told NBC4.

Watch NBC4's report below.