Between 1979 and 1985 a total of 8641 children were born at the gynecological clinic in Winterthur, 388 of them (4.5%) from breech presentation. All of these were evaluated with regard to external version, and conditions for an attempt at version were satisfied in 97 cases. The principal prerequisite was a gestational age of at least 37 weeks. External version was accomplished in 39 of the 97 cases (40.2%). Complications encountered were drops in fetal heart tone or bradycardias in 26 cases (26.8%); the attempt at version was abandoned for this reason in 22 cases. In one case premature detachment of the normally implanted placenta occurred 6 days after successful external version, and in one case an emergency cesarean section had to be performed owing to persistent bradycardia. In a further case intrauterine fetal death was established 18 hours after successful version on the basis of an absence of fetal movement, though no cause of death could be found. Among the 39 cases in which version was successful a cesarean section was only necessary in one (2.5%), as opposed to 21 in the 58 cases (36.2%) in which the attempt at version failed. Neonatal fetal condition (Apgar score and umbilical blood gas analysis) revealed that neonates born from vertex presentation are subject to very considerably less stress. The international literature is discussed and compared. It is found that there has been a change of trend from a tendency to reject external version in the 1970s to a majority favoring it in the 1980s.(ABSTRACT TRUNCATED AT 250 WORDS)