The Beta Mu Sigma Fraternity / Brotherhood of Medical Scholars (BMS) is the oldest, largest, strongest and only all-male organization in the PLM-College of Medicine. Founded on December 17, 1987, BMS stands through its four pillars namely: Brotherhood, Academic Excellence, Community Service, and Leadership.
BMS is the most awarded organization in the college. Awards garnered by BMS include: One of the Ten Most Outstanding Organizations of Manila for the years 1990, 1991, 1992 and 1995; One of the Three Most Outstanding Youth Organizations of Metro Manila for the year 1992; Presidential Award for the Most Outstanding Academic Organization in PLM for the years 1990 and 1991; Tanging Banggit Award for Community Service in PLM for the years 1990 and 1991 and most recently, the Molave Award for Most Outstanding Academic Organization in PLM for the year 2002. Likewise, BMS has received numerous certificates and plaques of merits from different organizations after rendering assistance and co-organizing projects with them including the Philippine National Red Cross Bronze Merit Medal Award 2007 for 10 years of volunteer service.
BMS boasts members excelling in community service, academic excellence and leadership. The organization has produced the likes of Christopher D. Reyes, the first ever board placer from PLM in the Physicians Licensure Examination; Allan L. Hilario Jr., Most Outstanding Student (PLM, 1991); Florante "Joey" L.  Lateo Jr, the first ever male cum laude in PLM-College of Medicine and one of the Ten Outstanding Students of the Philippines; and Jama Sy, 6th placer in the 1999 Physicians Licensure Examination. Moreover, BMS holds the distinction of having Mayo Yanilla as the only two-time consecutive president of the Supreme Student Council (SSC) of the Pamantasan. Other members elected as SSC President include Paul Salazar and Vladimir Untalan. At the college level, we have Darius M. Cruz as the College Representative of the 2008 College of Medicine Student council and Hermes T. Palad II as the incumbent SSC President for the school year 2008-2009. 
The organization is affiliated with various socio-civic, and non-government organizations which are both rural- and urban-based like Philippine National Red Cross, Ayala Foundation, Lion’s Club, Rotary Club, Remedios AIDS Foundation, PHYP, MAG, COMMED, CHD Bunso, BUKAS and KIWANIS Club. Recently, The Brotherhood of Medical Scholars Alumni Association Inc., a SEC registered Non-Government Organization, was establish for continued strengthening of the four pillars of this organization inside and outside the Philippines. Yearly projects headed by BMS include: booksales, medical and surgical missions, AIDS awareness campaign, bloodletting campaign, symposia, tutorials, gift-giving projects (Pasko na, Pedia ko!), sports activities (Medlympics), and Annual Inter-School Pre-Medicine Quiz Show.