The authors discuss their experiences from 412 chorion villus samplings, (CVS), which they have done under four and a half years since 1985. They used eight types of instruments in performing their examinations and each instrument proved to be satisfactory in the gaining of chorion villus samples, suitable for further tests. They also discuss the bacteria found most frequently in the vagina on the basis of the examination and culturing of both vaginal and cervical fluid done prior to 151 CVS examinations and the effective method with which ascending infection can be prevented. They discuss a distributional pattern of their results based on the different indications for the CVS examinations, and the outcome of each of the pregnancies after CVS. In 377 cases they did direct karyotyping, in 30 cases DNA examination and in five cases enzyme determination also occurred.