Reversal of twin-twin transfusion syndrome (TTTS) is a rare complication of monochorionic pregnancy. Diagnostic criteria and satisfactory therapeutic options have not been reported. We make a suggestion of diagnosis and therapy for reversal of TTTS. We report two cases of reversal of TTTS. Measurement of the fetal urine production rate was useful for management and better comprehension of the cases. In case 1, double intrauterine fetal demise occurred before the criteria for TTTS were fulfilled, in which each fetal urine production rate reversed prior to the change of amniotic fluid volume. In case 2, elevated urine production was noted prior to progressive polyhydroamnios and congestive heart failure in the new recipient and the fetoscopic laser photocoagulation of the placental communicating vessels was performed successfully before the criteria for TTTS were fulfilled. Both infants required intensive care, but developed normally and showed no neurologic complications at 2 years after birth. Hourly fetal urine production rate was useful for immediate diagnosis of reversal of TTTS, and laser photocoagulation of the placental communicating vessels is thus a method for the correction of the fetal blood flow imbalance in cases of reversal of the donor-recipient phenotype in TTTS.