Fifty-two transvaginal ultrasonographic examinations were performed between 10.0 and 14.9 weeks' gestation for the purpose of documenting normal fetal cardiac anatomy. All standard cardiac projections could be obtained by gestational week 12, and many were imaged by week 11. The four-chamber view was visualized in 90% of fetuses at 12 weeks' gestation and in 100% of fetuses examined at 13 weeks. The aortic root in short axis projection and the left ventricle in long axis view could be imaged in 70% and 40% of fetuses, respectively, by 12 weeks' gestation. Aortic and pulmonary valves were first visualized at 12 weeks, as were five-chamber, ductus arteriosus, and aortic arch views. The mitral and tricuspid valves were resolved in 60% of fetuses by 11 weeks' gestation. This study of normal cardiac anatomy suggests that there may be significant potential for the diagnosis of many fetal cardiac anomalies during the late first and early second trimesters of pregnancy.