Paulo Serodio, 45, is of Portuguese descent. But his family has lived in Mozambique for several generations.
He told ABC News that he got into trouble at the University of Medicine and Dentistry of New Jersey in Newark in March 2006 when an instructor, Dr. Kathy Ann Duncan, led students in a discussion, asking them for self-definitions.
Serodio's description of himself upset some other students, and he said Duncan later told him never to call himself an "African-American" again because some others found it "offensive."
Serodio said that he was suspended for unprofessional conduct after he made a similar comment in another class and then wrote an article in the student newspaper trying to explain his ethnic background. He said that other students also harassed him.
"I wouldn't wish this to my worst enemy," he said. "I'm not exaggerating. This has destroyed my life, my career."