Professor Hugh David Niall AO, the Australian medical researcher who cracked open the world of protein sequencing and helped clone the reproductive hormone relaxin, has died. He was 88.

Niall died on April 11, 2026, the Howard Florey Institute of Neuroscience and Mental Health confirmed. The institute where he spent much of his career called him a giant of Australian biotechnology.

Born in Melbourne on August 15, 1937, Niall was the fourth child of Dr Frank Niall, a cardiologist, and Connie Niall. His father died at just 53 in 1952, a loss that shaped Hugh's decision to study medicine.

He was a brilliant student. In 1954, Niall topped the state in his matriculation exams, coming first in Greek, Latin, calculus and applied mathematics. Xavier College suggested he do an arts degree first, but he went straight into medicine at the University of Melbourne.

At Newman College, he played cricket and tennis, edited the college magazine with future history professor Paul Bourke, and built friendships that lasted decades.

His big break came in 1958 when Professor John Hayden invited him to take a year out from medicine to work at the St Vincent's Research Centre. There, he met Swedish biochemist Pehr Edman, who had been denied a US visa during the McCarthy era. Edman gave Niall mastery in protein sequencing techniques — a skill Niall later took to the international stage.

Niall finished his medical degree, did two years as an intern at St Vincent's, and married Maggie Williams, a trainee biochemist, in October 1963. They had four children: Lucy, Jake, Ben and Emma.

The family moved to the United States, where Niall worked at the National Institutes of Health in Bethesda, Maryland, and later at Harvard Medical School. But the marriage broke down, and Maggie took the children back to Melbourne. Niall was devastated.

He left Harvard and, with colleague Geoff Tregear, negotiated new roles at the Howard Florey Institute in Melbourne. It was a risky move at a relatively early career stage, but it paid off. Their major achievement: cloning the reproductive hormone relaxin.

Relaxin is a hormone that relaxes the pelvic ligaments during childbirth and has since been studied for potential uses in heart failure and fibrosis. The cloning work put Australian biotech on the map.

Niall was appointed an Officer of the Order of Australia (AO) for his services to medical research. He also held an honorary Doctor of Medical Science degree.

His sister Margaret recalled that even as a toddler, Niall was determined and curious — once burning his hand on a hot stove after being told not to touch it. At age two, he pulled a medical book off the shelf, dropped it on his father's knee and demanded: "Talk it!"

That drive never left him. Niall is survived by his four children and his sisters, Margaret and Frances.