余仁生創辦人余廣培，廣東佛山人，年輕時在馬來亞開了一間名為仁生的中藥兼雜貨店。1891 年逝世後，其獨子余東旋接手父親的藥行生意，並於1909 年在香港開設分店。1920 年代，藥行正式改名余仁生，成為東南亞最大的中藥房。
Eu Yan Sang was founded by Eu Kwong Pui, a native of Foshan, Canton. He left his hometown for Malaya to earn a living when he was young and opened a Chinese medicine and grocery store called Yan Sang. After his death in 1891, his business was inherited by his only son, Eu Tong Sen, who expanded the business and opened a branch in Hong Kong in 1909. In the 1920s, the company officially changed its name to Eu Yan Sang and became the largest Chinese medicine company in Southeast Asia.
Hong Kong Chinese Merchants Collection keeps the business materials of Eu Yan Sang including 1,680 volumes of bound account books, auditor’s reports, remittance books, bank statements, Chinese medicine trade records, tax assessments and tax bills, and a large quantity of business letters, covering a period from 1915 till 1969.