John Hundale Lawrence (January 7, 1904 – September 7, 1991) was an American physicist and physician best known for pioneering the field of nuclear medicine.

There he discovered treatments for leukemia and polycythemia by injecting infected mice with radioactive phosphorus derived from the cyclotron invented by his brother, the Nobel Laureate Ernest O.

[3] He also demonstrated that neutron beams were potentially more effective at battling cancerous cells than X-rays,[4] and, in 1949, became the first physician to use a radioactively labelled noble gas for diagnostic purposes in humans.

[3] The experience of the Lawrence Brothers in nuclear medicine became crucial in saving their mother, when she was diagnosed with uterine cancer in 1937.

When they were told at Mayo Clinic that she had three months left to live, John Lawrence brought her to be treated by radiologist Dr. Robert S. Stone, one of his collaborators.