Chickenpox is an uncommon disease in women during pregnancy. If, however, maternal varicella infects the fetus, intrauterine death or severe diseases (congenital or fetal varicella syndrome) may ensue depending on the time of maternal infection. On the basis of our own clinical observations and virological testing we report on 31 women with varicella during pregnancy and their infants. Five neonates born to mothers with varicella between the 8th and 21st week showed clinical signs of the congenital varicella syndrome. Varicella-zoster virus DNA could be detected in different tissues, including lung, liver, skin and adrenal glands. As a consequence of maternal chickenpox within 12 days before delivery, 6 newborn babies developed neonatal varicella. Measures for diagnosis, treatment and prophylaxis are discussed.