Yehezkel was born on 15.5.1926 in Krakow to Yehoshua, a wealthy industrialist, and Mina née Blum Landau.  His father, who felt the winds of war blowing, travelled east with his family. They reached a camp in the Ural Mountains, and they had to work hard to survive. Finally, in April 1941, the family made aliyah, via Persia and Turkey. They settled in Tel Aviv.

Yehezkel studied in high school, and took external matriculation exams. In parallel, he worked in diamond polishing, and he saved money for medical school, inspired by losing his only brother to illness in 1943.

From1934 to 1942, Yehezkel was in the Hagana. In 1944, he joined Lehi and trained recruits, while serving on admission boards and in combat operations. He trained with firearms and explosives, and he took part on 25.2.1946 in the attack on Kfar Syrkin Airfield, in which RAF Spitfires were blown up.

In October 1946, Yehezkel went to study medicine in Switzerland, with his girlfriend Olga, daughter of Dr. Sigmund Weindling, his future wife. He continued his Lehi activity in the meantime, mainly in public relations and recruitment. He disseminated Lehi promotional material at the Twenty-Second Zionist Congress in Basel, and he travelled as an underground agent to France, Belgium, Prague and Poland. Olga also joined Lehi, and they married.

In 1948, he was drafted in Switzerland and was sent to train youths with weapons before aliyah. He then was summoned back to Israel to join the IDF’s Medical Corps.

Yehezkel became a specialist in internal medicine, while Olga became a pathologist. In 1957, he started researching hepatic steatosis, and in 1959, he received the Magnes Prize for it. He traveled to Yale University for postdoctoral research, as well as New York’s The Rockefeller University. Olga pursued cellular research. The couple collaborated, pooling their knowledge of medicine, biochemistry and more.

After they returned to Israel, Yehezkel resumed working at the internal medicine department of Hadassah Hospital in Jerusalem. He set up a program to treat hyperlipidemia, which became a national clinic and a training facility for doctors both for diagnosis and treatment.

When Professor Rachmilewitz retired in 1969, Stein was chosen to replace him. His tremendously successful fundraising allowed the construction of a full floor of research laboratories. Together with his wife, he has researched atherosclerosis. He has been a visiting professor at Columbia University and The Rockefeller University in New York; University of California, San Diego; and University of Washington in Seattle. He has won many prizes and honorary degrees in Israel and abroad, sometimes with his wife.

He served as the head of the European Atherosclerosis Society.

In 1996, he won the Israel Prize in medicine.