Hepatic concentrations of copper (Cu) and zinc (Zn) were studied in 38 fetuses and infants, who died of various causes, from 26 weeks of gestation up to 16 weeks post-natally. The six fetuses of 28-32 weeks gestation had median and mean hepatic Cu concentrations micrograms/g fresh tissue) comparable to those found in the 21 born at term, but the range of values was much narrower: all of the Cu values for those born prematurely were at or below 40 micrograms/g. Values at 10 micrograms/g and below were found in five infants at term and five who died at 1-4 months of age. There was a comparable range of Zn values for both pre-term and term babies (10 to 300 micrograms/g fresh tissue). The value of 10 micrograms/g was found only in one 4-month-old infant. The accumulation of both Cu and Zn occurs independently in the fetuses. The socioeconomic status did not influence significantly the concentration of liver Cu or Zn in babies born at term. However, size of babies as measured by liver weight showed that larger babies had significantly higher mean Cu concentration (37 +/- 24 micrograms/g) than smaller babies (21 +/- 14 micrograms/g. The same trend, but without significant difference, was observed for hepatic Zn between larger (104 +/- 78 micrograms/g) and smaller (74 +/- 59 micrograms/g babies.