Abstract Two hundred two cases of constriction ring dystocia are analyzed in regard to frequency, diagnosis, and treatment. The frequency was found to be 1.67 per cent. There is a general impression that this condition is rarer than my figures would indicate. It is quite possible that many cases are overlooked. Cases are cited to show that some difficult forceps operations may be rendered easy if the constriction ring be relaxed with epinephrine. Epinephrine was used to relax the constriction ring in 150 cases. It failed eight times. Twenty cases occurred before it was known that epinephrine would relax the ring. Of these, one mother and nine babies were lost. One hundred eighty-two mothers and 183 babies (one set of twins) were seen after the advent of epinephrine. There was no maternal death, and the fetal mortality was 17.5 per cent. Eleven of these infant deaths occurred in the first 23 cases. As experience with this drug grew, the results improved.