Ko Kuei Chen (Chinese: 陳克恢; pinyin: Chén Kèhuī; 26 February 1898 – 12 December 1988) was a Chinese-American scientist who led pharmacological research at Eli Lilly and Company for 34 years.

After studying at Tsinghua College in Beijing, he moved to the United States in 1918 to further his education, earning a BS in 1920 and a PhD in 1923 from the University of Wisconsin-Madison.

He continued working at Johns Hopkins for a couple of years before accepting an offer in 1929 from Eli Lilly and Company to be the Director of Pharmacological Research.

Other studies that may be credited to him include the successful treatment of cyanide poisoning with nitrite-thiosulfate therapy, structure-activity relationship of over 400 cardiac glycosides and toad venom steroids, heptatotoxic action of Senecio alkaloids, and synthetic analgesic drugs of the methadone series.

In order to help his ailing mother, he returned to China, continued his research, and taught classes at Peking Union Medical College.