The results of 552 amniocenteses during the second trimester of pregnancy are reported. The amniocentesis were carried out under direct ultra-sonographic control. Six abnormal karyotypes were found and the pregnancies were terminated. Three spontaneous abortions due to intra-uterine infection following amniocentesis occurred. There were no maternal complications and no fetal injuries. 430 amniotic fluids were tested bacteriologically. Two samples showed E-coli and two samples grew staph epidermidis. The IGM values of 148 newborns with previous amniocentesis showed the same values as the IGM in newborns without amniocentesis during the pregnancy. Fetal monitoring prior and following the amniocentesis showed a temporary increase in uterine motility in 25% of the cases. Our observations and the review of the literature convinced us that complications of amniocentesis in the second trimester are rare. However, when complications occur the fetus and the pregnant woman are a serious risk. The fetal wastage caused by second trimester amniocentesis is approximately 0.5 to 1%. Therefore the patients must be informed about the risks very carefully prior to a second trimester amniocentesis.