The zinc concentration of amniotic fluid (AF) of 129 pregnant women was analyzed by the flame atomic absorption spectrometry. This prospective study was performed in order to find out whether the determination of the AF zinc concentration can be used to monitor the growth and development of the fetus. There were two groups of patients: early stage (15th-19th gestation wk) in which the amniocentesis was performed as a prenatal genetic examination, and late stage (26th-40th wk) in which the amniocentesis was performed due to obstetric reasons. The average AF zinc concentrations were 1.2 and 1.0 μmol/L in the early and late gestation group, respectively. The AF zinc concentration did not correlate with the weight, height, or Apgar scores of the newborn nor with the maternal diseases, age, or parity. The AF zinc concentration in the late gestation group was significantly lower if the fetus was male than if it was female. If the AF was greenish the zinc concentration was elevated. One malformation, congenital nephrosis, with an exceptionally high zinc concentration (9.0 μmol/L), was found.