Gasnier became Australia's youngest ever captain in 1962 when he led Australia against England at 23 years and 28 days. The following season, he toured Europe as a member of the National Team for a second time. In 1967-68, he again toured Europe, this time as coach-captain of the Kangaroos. His career ended prematurely, at age 28, when he broke his leg during the first test at Headingley Rugby Stadium, Leeds, that saw him sit out the remainder of the English leg. He returned to the field in France but in a minor game against Les Espoirs in Avignon, he suffered a further break of the leg. This would ultimately cause him to announce his retirement from playing at the age of just 28. He later told in an interview that he never regretted his decision to retire, explaining that he had been playing rugby league virtually non-stop including juniors, junior representative games, the Sydney premiership, interstate games and international tours since the early 1950s, and felt it was about time that he started devoting more time to his family.