Phi Chi, one of the oldest medical fraternities in the world, was established on March 5, 1905. It was formed by the merger of two professional medical fraternities with the same name. Phi Chi Society (Phi Chi East) was founded on March 31, 1889, at the University of Vermont. Phi Chi Medical Fraternity (Phi Chi South) was founded on October 26, 1894, at the Louisville Medical College. These two organizations did not know they shared a similar name when they were founded. 
On March 5, 1905, in Burlington, Vermont, Phi Chi Society and Phi Chi Medical Fraternity, Inc., were consolidated taking the name Phi Chi Medical Fraternity, Inc. Phi Chi East had five active chapters at the time of the merger. Phi Chi South had eighteen active chapters at the time of the merger. Phi Chi also merged with the Pi Mu Honor Society on October 7, 1922, acquiring a new chapter and absorbing six chapters.
Chapters.
When the Phi Chi Society and Phi Chi Medical Fraternity combined in 1905, it was decided that when the names of any two chapters conflicted, the chapter with precedence would retain its single-letter name and the chapter with the later chapter date would duplicate its name. The result was retaining the "Alpha chapter" (1889) at the University of Vermont as named, and renaming the former "Alpha chapter" of Louisville (1894) as "Alpha Alpha chapter", and so forth.
Following is a list of chapters. Active chapters are indicated in bold. Inactive chapters are in "italics".
References.
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