Selected clinical features of the course of pregnancy in 118 gravidas with placenta praevia diagnosed ultrasonographically on the first breeding were compared. The clinical features significantly connected with bleeding and the prognostic features for the way of delivery were stated. The longest bleeding was observed in patients with partial or marginal placenta praevia. The most common anterior location of low placenta praevia was connected with the lowest risk as regards the cesarean section due to hemorrhage. The earlier occurrence of the bleeding was associated with its longer duration. The time of the occurrence of the first bleeding and its duration were associated with a duration of the pregnancy and a body mass of the newborn. The recurrence of bleeding was of no prognostic importance. The appearance of the first bleeding after the 28th week of pregnancy was significantly connected with the necessity of performing a cesarean section due to hemorrhage in case of central, partial or marginal placenta praevia. In case of low-lying placenta the way on delivery was significantly related to the time of appearance of the first bleeding and the distance between the placenta and the internal os. Fisher's linear discriminative function of the two features allowed for the determination of a mathematical formula for the prognosis of the way of delivery in case of a low-lying placenta.