Green represented the United States as an 18-year-old at the 1952 Summer Olympics in Helsinki, Finland.

[1] She competed in the women's 400-meter freestyle, advanced to the event final, and finished fourth in a time of 5:16.5.

[1][3] At the 1951 Pan American Games in Buenos Aires, Argentina, she won a gold medal as a member of the winning U.S. team in the women's 4×100-meter freestyle relay, together with American teammates Jackie LaVine, Betty Mullen and Sharon Geary.

[1][3] Individually, she received a silver medal for her second-place performance in the women's 400-meter freestyle.

[3] Four years later at the 1955 Pan American Games in Mexico City, she again won a gold medal in the women's 4×100-meter freestyle, this time with teammates Judith Roberts, Wanda Werner and Gretchen Gluter.