um Nung, master of masters, is the prime disciple of grandmaster Yuen Kei San. At a very young age, he learned Wing Tzun from Cheung Po and medicine from Wei Yok Saun. He later became a disciple of Yuen Kei San. D.r Sum Nung has almost 60 years of experience in Wing Tzun. He is ranked as one of the top 10 doctors in China and considered one of the top 9 martial artists in the world.

Dr. Sum Nung is the authority in Yuen Kei San Wing Tzun. He has taught advanced disciples such as  Leung Tai Chiu (King Leung), Wong Tiet Wai (Teddy Wong), Ngo Lui-Kay, and Tommy Wong who teach in North America. Other students, internationally, include Kwok Won Ping, Lee Chi Yiu, Oliver Cheng, Yuen Jo-Tong, and an additional few.

Dr. Sum Nung and the late Yip Man were friends in his youth. Yip Man became the head of the Hong Kong branch of Wing Chun while Dr. Sum Nung is considered the head of the Guangzhou Wing Tzun in China (also known as Yuen Kei-San Wing Tzun).

One of Sum Nung's top student's is Leung Tai Chiu. Not only did he complete the Wing Tzun training, but he also completed the medical training under Dr. Sum Nung. Leung taught Guangzhou Wing Tzun in Hong Kong in the 70s and with the help of his kung fu brother, Dr. Teddy Wong, he migrated to the United States where he taught several students, including Dr. Wong's three children, in the 80s. Leung is currently concentrating on his business and practices medicine on the side.

Wong Tiet Wai (Teddy Wong), began learning kung fu at the age of 9 and his entire life has been dedicated to the martial arts. He first learned Mi Jon (Lost Track) from Lau Jok Fung who was one of the higher level students of the Jin Mo (Ching Woo) school founder, Fok Yuen Ja. He then learned Mok Gar (Shaolin kicking style) from Dr. Cheung Wing Fei. The style that attracted him the most, however, was the Yuen Kei San Wing Tzun that he learned under Dr. Sum Nung. Sifu Wong has been teaching Yuen Kei San Wing Tzun since the 70s. He holds a doctorate in mathmatics from NYU and is currently a Chairperson in the mathmatics department of a NYC college. Known to be amongst the favorite students of Dr. Sum Nung, sifu Wong has proudly produced many advanced students over the years, such as Dean Wallace, Vasco Montez, Mike Engle, Paul Tsang, Hector Bourren, Giovanni Falconi, Steve Arboleda, Mike Cavaliere, and others. His students come from a wide range of backgrounds, including doctors, police officers, federal agents, engineers, etc.