[3] In 1967, Chrétien opened a laboratory on polypeptide hormones at the Clinical Research Institute of Montreal (CRIM), where he would remain until 1999.
In 1999 he was scientific director and CEO of the Loeb Health Research Institute at the Ottawa Civic Hospital.
In 2006, he was appointed Senior Scientist of Hormone, Growth and Development at the Ottawa Health Research Institute.
[3] In 1986, he was made an Officer of the Order of Canada in recognition for being "at the forefront of Canadian scientific research and an international leader in the field of neuroendocrinology".
[3] In 2009, he was elected a Fellow of the Royal Society[10] In 2017 he was made a member of the Canadian Medical Hall of Fame.