We evaluated the trends and risk factors in infant mortality in Israel over five decades (1950-2000), based on data obtained from the official notifications of live births, and death certificates. Until the 1960s the main cause of infant mortality was infectious disease; this was replaced by congenital anomalies in Moslems and Druzes, and preterm birth in Jews and Christians. In 2000, there were 746 infant deaths, and the national infant mortality rate (IMR) was 5.4 per 1000 live births (Jews 3.9; [95% CI 3.5, 4.3]; Moslems 9.2 [8.3, 10.3]; Christians 3.6 [1.4, 5.8]; Druzes 6.3 [3.6, 9.0]). Between 1955 and 2000 the overall IMR declined sevenfold (absolute declines of 56.8, 56.3, 45.0 and 28.3 per 1000 live births, in Moslems, Druzes, Christians and Jews, respectively). The reduction in IMRs between 1990 and 2000 in all religious groups (>45%) exceeded the goal set by the World Summit for Children in 1990 of 33%. In 2000, the main risk factors were birthweight < 1500 g [relative risk (RR) = 69], major congenital malformations (RR = 22.0 [18.8, 25.7], and multiple births (RR of 9.3 and 4.2 in triplets and twins respectively). We conclude that the marked decline in IMRs in Israel over five decades reflects a major improvement in population health. Today, infant mortality in Israel represents a unique combination of high rate of congenital malformations among Moslems, where consanguineous marriages are common, and medical termination of pregnancy of malformed fetuses are infrequent; and relatively high IMRs from preterm birth in Jews, associated with high rates of assisted reproduction.