Between 1950-54 and 1970-74 the mortality rates from breast cancer showed a 35% increase in Italy. In the city of Torino, an increase occurred between 1950-54 and 1960-64 but not in the following 10-year period. These trends were confirmed by the analysis of rates by cohorts of birth. In the province of Torino, between 1960-64 and 1970-74 the increase in breast cancer death rates was far lower than in the other provinces of Piedmont. It is suggested that the peculiar patterns in the city and in the province of Torino reflect qualitative changes of lifestyle brought about by the conspicuous immigration from southern Italy during the sixties.