The University of Maryland was the first program in the state to offer chorionic villus sampling (CVS). Since the program's beginning in 1984, 998 patients have been seen with successful sampling in 99.1 percent, using both transcervical and transabdominal approaches. The overall loss rate was quite low (2.3 percent), and no increased risk of birth defects was seen. These observations demonstrate that CVS provides a safe and accurate alternative to amniocentesis.