American biochemist and pharmacologist who, along with the British biophysicist Sir Bernard Katz (Katz, Sir Bernard) and the Swedish physiologist Ulf von Euler (Euler, Ulf von), was awarded the Nobel Prize for Physiology or Medicine in 1970. Axelrod's contribution was his identification of an enzyme that degrades chemical neurotransmitters within the nervous system after they are no longer needed to transmit nerve impulses.

A graduate of the College of the City of New York (B.S., 1933), New York University (M.S., 1941), and George Washington University (Ph.D., 1955), Axelrod worked as a chemist in the Laboratory of Industrial Hygiene at New York City's Health Department (1935–46) and then joined the research division of Goldwater Memorial Hospital (1946), where his studies on analgesic medications helped identify acetaminophen as the chemical responsible for relieving pain. Marketed under such trade names as Tylenol and Panadol, acetaminophen became one of the most widely used painkillers in the world. In 1949 Axelrod left the hospital to join the staff of the section on chemical pharmacology at the National Heart Institute in Bethesda, Maryland. In 1955 he moved to the staff of the National Institute of Mental Health, where he became chief of the pharmacology section of the Laboratory of Clinical Sciences. He remained at the institute until his retirement in 1984.

Axelrod's Nobel Prize-winning research grew out of work done by Euler (Euler, Ulf von), specifically Euler's discovery of noradrenaline (norepinephrine), a chemical substance that transmits nerve impulses. Axelrod, in turn, discovered that noradrenaline could be neutralized by an enzyme, catechol-O-methyltransferase, which he isolated and named. This enzyme proved critical to an understanding of the entire nervous system. The enzyme was shown to be useful in dealing with the effects of certain psychotropic drugs and in research on hypertension and schizophrenia.