Objective To control the birth of children with thalassemia by applying prenatal diagnosis to high risk pregnancy. Methods Chorionic villi samplings were performed in 1 072 pregnancies of gestational age of 10 to 15 weeks for the gene detection of α- or β-thalassemia. Results Out of 1 072 chorionic villi samples,727 were given gene analysis of α-thalassemia,568( 78. 13%) were carriers with α-thalassemia; 336 were given gene analysis ofβ-thalassemia,256( 76. 19%) were carriers with β-thalassemia; 9 were given gene analysis of α- and β-thalassemia,all of which were carriers with thalassemia. There were 142 cases of Hb Bart's disease and 75 cases of homozygous or double heterozygous β-thalassemia,they all received termination of pregnancy within one week after prenatal diagnosis.Conclusion Chorionic villi sampling is a feasible and effective technique for prenatal diagnosis of thalassemia,which might effectively control the birth of children with thalassemia.