The authors observed 25 pregnant or delivering women with varicella and their offsprings from 1986 to 1991. The course of varicella of the pregnant and delivering mothers was generally benign, only one progressive case was observed with pneumonitis after delivery; this woman also recovered upon acyclovir treatment. All but one woman delivered on term, in one case the varicella developed on the 27th gestational week; this woman gave birth to a premature baby of 1180 g who died from a cerebral and lung hemorrhage. No sign of varicella-zoster virus infection was found at the autopsy. No congenital varicella syndrome was observed during the investigation period. Varicella-zoster immunoglobulin was given to 21 newborn babies, immediately after birth. Eight of the newborns developed varicella, the course of the disease was mild in seven cases. One baby who was given no varicella-zoster immunoglobulin and developed progressive varicella recovered after acyclovir therapy. During the investigation period the authors observed three cases of zoster in infants whose mothers had had varicella during pregnancy. The authors discuss the possibilities of prevention of varicella-zoster virus infection of newborns and infants.