Phi Sigma (ΦΣ) is an honor society for students of biological sciences, formed at Ohio State University.

[1] In 1947, Phi Sigma became international when it established a chapter at the Universidad Nacional Autónoma de México.

Fellowship in science includes ardent cooperative effort, effective leadership, and creative scholarship.

[1] Phi Sigma's emblem consists of a watch key fob formed of the Greek letters Φ and Σ, the former being superimposed upon the latter.

[1] Phi Sigma is reserved for students who have demonstrated interest in research and are inc the top 35 percent of their class with a 3.0 GPA.