The British Medical Journal is launching a competition to decided the greatest medical breakthrough.
Present-day medical experts are championing discoveries from the last 166 years.
Dr Stephanie Snow of the Centre for the History of Science, Technology and Medicine at the University of Manchester says anaesthesia deserves to win.
People have sought relief from the pain of operations since they began.
A chloroform inhaler developed by John Snow
Alcohol and opiates were initially used, but were soon rejected due to their depressive effects and because they increased the risks of surgery.
Ether was the first substance to be successfully used as an anaesthetic during William Morton's experiments in Massachusetts in 1846.
But it was a UK doctor, John Snow in London, who realised there could be different degrees of anaesthesia - a discovery which still informs practice today.
However, ether could make it difficult to breathe, and inhalers often did not provide a large enough dose.
But in 1847, James Young Simpson, a Scottish obstetrician discovered the anaesthetic effects of chloroform.
It soon replaced ether, and led to operations becoming much more common for small injuries as people did not have to bear the pain.
But its use to relieve pain in childbirth only became widespread after John Snow administered chloroform to Queen Victoria for the births of Prince Leopold in 1853 and Princess Beatrice in 1857.
Since then, anaesthesia has continued to develop with the 20th century seeing the introduction of muscle relaxants and spinal anaesthesia amongst others.
Dr Snow, a descendent of John Snow, said: "The detail of anaesthesia will surely continue to evolve.
"But nothing is likely to be as significant as the early demonstrations of ether's potential to alleviate the pain of surgery."