Koh Kim Yam was born in Muar, Johor, in 24 Jan 1915, fourth son of the merchant, Koh Peng Chiang (who had property holdings in Singapore and Johor). He was grew up on Balmoral Road and was schooled at St Joseph's Institution, where he obtained his Senior Cambridge (equivalent to GCE O-levels) at the age of 15. and obtained his Licenciate in Medicine from King Edward VII College just before the outbreak of war. While still a medical student, he met his future wife, Miss Choo Ngai Mun, a midwifery student from Kuala Lumpur. He was in Singapore during the Japanese invasion, but refused to serve under the Japanese in Singapore. Dr Koh was therefore posted to the psychiatric hospital in Tanjong Rambutan, Perak, taking Miss Choo with him. They married in 1942 in Kuala Lumpur. His first two sons, Richard and Patrick were born in 1943 and 1944 respectively in Tanjong Rambutan. In December 1944 he was take by the Japanese to care for Malayan coolies working on the Siam-Burmese railroad, where he remained until the Japanese surrender. Not knowing whether her husband was dead or alive, Mdm Choo returned with her two small children to her family in Kuala Lumpur. Dr Koh continued to work in Siam under the Royal Army Medical Corps for some months after the Japanese surrender, but returned to Singapore in 1946, when he was appointed to run the re-opened Tanjong Pagar Clinic on Nelson Road, Tanjong Pagar, where his third son, Francis was born. The Nelson Road clinic cared primarily for port workers and sailors, and "social health" (a euphemism for sexually transmitted diseases) was therefore a large part of his practice there. The environment was very sooty because of smoke from the nearby port, and so in 1954, Dr Koh purchased a house in the newly build Sennett Estate, at 21 Butterfly Avenue for $46,000, which remained the family home the rest of his life. In 1960, Dr Koh was appointed medical officer-in-charge of the Middle Road Hospital, in which post he remained until his retirement in 1970. After retirement, he continued to work as a temporary medical officer at Middle Road Hospital. We was an active golfing member of Island Country Club. He died in his sleep in April 1976.