Yuan Chang (simplified Chinese: 张远; traditional Chinese: 張遠; pinyin: Zhāng Yuǎn; born 17 November 1959) is a Taiwanese-born American virologist and pathologist who co-discovered together with her husband, Patrick S. Moore, the Kaposi's sarcoma-associated herpesvirus (KSHV) and Merkel cell polyomavirus, two of the seven known human oncoviruses.

Chang trained in neuropathology at Stanford University under the noted clinical neuropathologist, Dikran Horoupian, publishing studies on eosinophilia-myalgia syndrome and progressive multifocal leukoencephalopathy.

During this period she contributed to studies led by her friend, Julie Parsonnet, showing that Helicobacter pylori is a cause for gastric cancer.

In 1994, she co-discovered KSHV,[1] also called human herpesvirus-8 (HHV-8), working with her husband Patrick S. Moore at Columbia University.

[3] Chang is now the American Cancer Society Professor in the Department of Pathology at the University of Pittsburgh.