James Sneddon Jeffrey, MD, FRCSEd (12 August 1904 - 30 May 1989) was a Scottish surgeon who worked for most of his career at the Royal Infirmary of Edinburgh (RIE).

His reports concluded that Penicillin in this context, should be used early in the treatment of infected wound rather than at the later stage of chronic suppuration.

[3] In 1939 he was awarded the degree of Doctor of Medicine (MD), for a thesis entitled Regional ileitis: a clinical and experimental study.

Although there had been earlier descriptions, most notably that by Sir Kennedy Dalziel, it was Burrill B Crohn and his colleagues in a seminal 1932 paper who gave the first comprehensive account of the clinical and pathological features.

[7] Jeffrey was called up in 1939 and served as a major in the Royal Army Medical Corps (RAMC) with the British Expeditionary Force in France and was evacuated from Quiberon Bay back to England.

Jeffrey was promoted to Lt Colonel and appointed Surgical Penicillin Officer in the team which carried out the assessment.