This study investigated the effect of clamped and unclamped cord on third stage of labor in two patient groups and correlated the drained placental blood volume with the newborn hematocrit. In the first group (trial group, n = 215) the placental part of the cord was left unclamped and the drained blood volume was measured. In the second group (control group, n = 199) the placental part of the umbilical cord was left clamped. Both groups were nearly equal regarding history, age and parity. The following results were obtained: Unclamped umbilical cord was associated with a shorter third stage of labor, unclamped umbilical cord was associated with less blood loss during third stage of labor, unclamped umbilical cord was associated with fewer operative procedures (i.e. manual removal of the placenta), differences regarding the number of incomplete or possibly incomplete placentae were not evident, a highly significant negative correlate was found between placental blood volume drained from the umbilical cord and newborn hematocrit (r = 0.38; p less than 0.001).