Alpha Chi Sigma (ΑΧΣ) is a professional fraternity specializing in the fields of the chemical sciences.

[1] It has both collegiate and professional chapters throughout the United States consisting of both men and women and numbering more than 78,000 members.

The fraternity aims to bring together students and professionals pursuing a wide variety of chemistry-related careers.

The Alpha Chi Sigma fraternity was organized at the University of Wisconsin–Madison by a group of undergraduates who were fellow students in chemistry at that time.

The founders were: The Three Objects of Alpha Chi Sigma:[2] The Five Obligations of a Member:[2] The fraternity's colors are Prussian blue and chrome yellow.

[3] Its coat of arms includes a shield with a Prussian blue background that is bisected by a diagonal chrome yellow bar that features the symbols of the seven metals of the Ancients.

After the guidelines set up in the bylaws are fulfilled, the group can petition the Supreme Council to grant it chapter status.