Factors affecting the fetal glucose level can be of maternal, placental or fetal origin. The level of fetal insulin during gestation 1s regulated by the potential of the endogenous fetal production on one hand, and on the other, by the factors (primarily glycaemia) that stimulate or inhibit its production. The aim of this paper was to analyze in which way and to what extent congenital infection with the cytomegalovirus disturbs the metabolism of fetal glucose and insulin. Umbilical venous cord blood was obtained by cordocentesis at 22 to 29 weeks gestation from 52 women referred to our chmc for fetal karyotyping and scatological analysis of fetal CMV infection. To determine the effect of cytomegalovirus (CMV) infection on insulin and glucose fetal homeostasis, cordocentesis was performed in 18 patients (group A) with proven congenital CMV fetal infection. The control group (B) consisted of 34 patients in whom blood samples were taken for fetal karyotyping. Maternal and fetal glucose levels were 3.95 mmol/L and 3.15 mmol/L in group A and 4.00 and 3.62 mmol/L in group B, respectively. Maternal average insulin level in group A was 14.45 mU/mL and in fetuses 10.64 mU/mL, while in group B maternal and fetal insulin levels were 12.38 mU/mL and 15.35 mU/mL, respectively. Maternal/fetal (M/F) insulin ratio was 1.35 in group A and in group B, 0.84. Statistical analysis showed significantly lower glucose and insulin levels and also a higher maternal/fetal insulin ratio in fetuses affected by CMV infection (t = 1.4 p,0.001). Consequences of congenital CMV infection were fetal hypoglycaemia and hypoinsulinemia.