In the years 1985-1987, 274 transcervical chorionic villi biopsy samples were taken at the Klinikum Steglitz Medical Center of the Free University of Berlin. We have information on the outcome of 264 pregnancies (96.3%). 229 cases (83.6%) yielded diagnostically usable results. Multiple biopsy samples were taken in 59 (21.5%) cases. Abnormal results were found in 14 patients. Pregnancy was terminated in 6 cases (2.2%) for proven chromosomal aberrations. In two others, spontaneous abortion occurred before the intended induced abortion. In 4 cases of mosaics, amniocentesis was performed subsequently in the 16th week of pregnancy; three of those pregnancies were carried to full term, and the children are healthy. In one case, we saw a spontaneous abortion in the 26th week of pregnancy. In two cases, we found balanced translocations. Miscarriage was observed in 16 CVS patients (5.8%). Abortion was febrile in two cases, septic in two others.