Exposure to environmental pollutants can result in chromosomal instability, which can produce a wide variety of effects on human health. In the spring of 1999, extensive environmental pollution happened in Kragujevac (the city in the central Serbia) with damages of soil, water and air, caused by the air strikes on "Zastava" complex. Because we found significant increase of micronuclei in newborns born 12 months after this environmental pollution (in the beginning of 2000), the purpose of the present study was to follow the frequency of micronuclei in lymphocytes of newborns born seven years after pollution (in 2006). The frequencies of micronuclei were estimated in cord blood lymphocytes of 41 newborns (20 males and 21 females) by application of cytokinesis-block (CB) micronucleus test. The obtained results showed that the mean value of micronuclei was significantly decreased in newborns born in 2006 in comparison to the mean value of micronuclei in newborns born 12 months after contamination (4.73 +/- 3.38 micronuclei/1,000 CB cells vs 9.36 +/- 5.60 micronuclei/1,000 CB cells), with probability p < 0.001. Newborn's gender, mother's age (19-40 years) and maternal cigarette smoking (< 20 cigarettes per day) did not show any noticeable effects on micronuclei frequencies in the analyzed newborns. There was relationship between the micronuclei frequencies and the level of environmental pollution (F = 6.95, p = 0.000). Our results suggest that the environment profoundly influences genetic constitution of newborns, and that micronucleus assay in cord blood lymphocytes is an important method for evaluation of transplacental mutagens.