We report on 14 observations undertaken by ourselves of silent persistent ductus arteriosus (SPDA). During a three year period with the routine use of color doppler flow evaluation we found cases of SPDA in 14 children. A very little ductus arteriosus is already known to us through earlier heart catheter examinations which were undertaken because of other isolated heart defects (16 cases in 345 isolated heart defects over 10 years). We also consider the fact that SPDA is not an infrequent result after the occlusion of a patent ductus arteriosus with the Rashkind-Occluder-System and after operative ligatures of patent ductus arteriosus. Finally, we compare our results concerning the frequency of SPDA with current literature and discuss consequential therapies.