Varicella during pregnancy can be associated with severe illnesses for both the mother and her neonate. Varicella pneumonia must be regarded as a medical emergency, since pregnant women are at risk of life-threatening ventilatory compromise and death. After maternal chickenpox in the first and second trimesters, congenital varicella syndrome may occur in nearly 2% of the cases. The characteristic symptoms consist of skin lesions in dermatomal distribution, neurological defects, eye diseases and skeletal anomalies. If the mother develops varicella rashes between day 4 (5) antepartum and day 2 postpartum, generalized neonatal varicella leading to death in about 20% of the cases has to be expected. Normal zoster has not been shown to be associated with maternal pneumonia, birth defects or problems in the perinatal period. On the basis of the clinical consequences of varicella-zoster virus infections during pregnancy, the present paper summarizes the currently available concepts of prevention, diagnosis and therapy.