An analysis was made of the influence of maternal diet and serum lipids during the third trimester of pregnancy upon cord blood lipids in two populations of Spanish newborns. A significant correlation was found to exist between maternal cholesterol concentrations and those of newborn infants (r = 0.3298). A correlation was also found between maternal cholesterol levels and infant HDL-cholesterol (r = 0.2575) and LDL-cholesterol (r = 0.3053) levels. Further, a positive correlation was seen between maternal LDL-cholesterol and infant cholesterol (r = 0.3204) and LDL-cholesterol (r = 0.3507). The relationship between maternal cholesterol and cord blood cholesterol was independent of participants' dietary, anthropometric and personal data. 3.1% of neonates showed total cord blood cholesterol concentrations of > 2.6 mmol/L. The mothers of these children showed the strongest concentrations of cholesterol and LDL-cholesterol in the third trimester of pregnancy, the shortest pregnancies and the smallest newborns of all subjects. Negative correlations were found between birth weight and cord blood cholesterol levels (r = -0.1475) and LDL-cholesterol (r = -0.1686). It might be deduced from these results that a relationship exists between the maternal blood lipid parameters studied and those of the cord. Inverse relationships were also seen to exist between the lipid parameters of cord blood and weight at birth and length of pregnancy. These data have implications that deserve further study.