[Infant mortality in Chile: the great descent].

Infant mortality in Chile decreased from 120 to 12 per thousand between 1960 and 1994. Outstanding events of this "great descent" are reviewed, based on past research and on updated information. Demographic and socioeconomic changes and improvements in health care that occurred during this period of decline are shown. It is estimated that 30% of the reduction of infant mortality between 1972 and 1982 was due to the decreasing proportion of births of high mortality risk, as a consequence of the fertility decline initiated in the mid 60s. Possible explanations for the continuing decline of infant mortality during the economic crisis of 1975 and 1982 are discussed. Finally, neonatal and postneonatal mortality rates by causes are compared between 1994 and 1980 and causes of death in extreme groups of infant mortality differentials by age of mother, birth order, gestational age, place of residence and educational level of the mother are shown.