The advent of ultrasound recording has expanded the capabilities for treatment of the fetus in utero. The diagnosis of specific disease processes has allowed for prenatal intervention by new techniques designed to improve fetal survival. The application of ventricular pacing in a hydropic fetus with complete atrioventricular (AV) block is reported. Complete AV block resulted from maternal collagen vascular disease. The application of ventricular pacing was to allow for further in utero development and for reversal of hydrops fetalis after improvement in cardiac output. Despite fetal death 4 hours after placement of the ventricular pacing lead, this procedure when applied earlier in the development of hydrops may allow for fetal survival. Ventricular pacing was accomplished without apparent trauma to mother or fetus and no evidence of fetal injury was seen at necropsy. Therefore, in the fetus who would otherwise die in utero before the point of viability ex utero, fetal ventricular pacing may be a rational alternative to current observation.