A search has been conducted in Canada on 222,000 blood samples, for haemoglobin variants detectable electrophoretically. A pattern of Hbs A + J was found in 41, and of these, 23 have been identified as J Baltimore (in 18), J Toronto (in 1), j. Broussais (in 3) and St. Claude (in 1). 12 instances of J Baltimore and one of J Toronto came from English Canadians, while the remainder came from French Canadians. Of those not identified, five were considered to be Jα and 13 Jβ variants. The known distribution and incidence of J Baltimore, and of the Hbs J that have been found in the indigenous populations of the United Kingdom and of France, are reviewe