Introduction: One of the techniques used for prenatal diagnosis is CVS. In contrast to amniocentesis (AC) carried out between 16 to Abstract of the 8th Royan International Twin Congress, Tehran, Iran, 5-7 September 2007 56 Yakhteh Medical Journal, Vol 9, Sup 1, Summer 2007 18 weeks gestation (second trimester), CVS can be done before 12 weeks of gestation (first trimester). Currently CVS can be done using both trans-abdominal (TA) and Transcervical (TC) techniques. Both methods are done between 9th and 11th weeks gestation under the ultrasound guidance. There is however controversy as to which technique is better, although TC is preferred when placenta is in a posterior position. Compared to amniocentesis, there is a higher miscarriage rate following CVS. Brambati et al (1991), in a randomized study showed that miscarriage rate in CVS done by TA was 16.5% compared to 15.5% in TC method. Various studies have demonstrated that CVS done by TC encounters more bleeding and sampling might need repeating. Since the current CVS methods inherit some problems such as bleeding and miscarriage, there is therefore a need for a safer method. In this study a new technique for CVS using transvaginal myometrium (TVM) has been introduced. Materials and Methods: we investigated 362 patients referred to Sarem hospital from different genetic centers in Tehran. CVS was carried out on the patients using either TC or TVM randomly. All the patients were monitored by ultrasound and those with demised fetus, unsuitable anatomy, occurrence of bleeding in the previous week, twin pregnancies, and cervical fibroma were excluded from the study. The patients were aware of the CVS technique and its disadvantages. For TVM procedure the patients were placed in a lithotomic position. The vagina was cleaned using sterile swab and physiological saline. The position of fetus and placenta was monitored using ultrasound with vaginal probe. After positioning placenta in the movement path of a needle placed in a special guide and over the vaginal probe, the needle was directly inserted in the placenta through adjacent furuncles and myometrium. A 20 ml syringe containing 5cc culture medium and heparin was attached to the needle. Using negative pressure the villus was aspirated inside the syringe and with the same pressure, the needle was removed from the placenta and myometrium. Using dissection microscope the villus was checked and then the patient was transferred to the recovery room. CVS using TC was done using standard techniques. Results: For three patients CVS was repeated on the same day. The average age of the patients was 28.9± 7.4. years. CVS was carried out at 10.8± 1.5 weeks. Following CVS with TC method, there was one miscarriage, one oligohydramnio, and one case with bleeding. In contrast TVM technique had no adverse effect. Conclusions: CVS using TVM technique seems to be a safe technique and a better alternative to TC. However for a more conclusive result, further studies using a bigger sample size is warranted.