Abstract： Objective To evaluate the effectiveness and safety of invasive procedures of prenatal diagnosis for twin gestations through analysing the results and outcomes of twins.Methods Invasive prenatal diagnostic procedures guided by ultrasound were introduced to 164 twin pregnancies with various indications,including 111 amniocentesis,and 53 cordocentesis.The results of prenatal diagnosis,complications and outcomes of these twins were analyzed with Chi-square test or Fisher's exact test.Results (1) Chromosome was examined in 261 fetuses and 6.13% (16/261)had abnormal karyotypes.(2) Comparing amniocentesis with cordocentesis,the fetal loss rate within two weeks after the procedure were 0.00% (0/191) and 3.85% (3/78),respectively (P=0.024).The total fetal loss rate and preterm delivery rates in amniocentesis and cordocentesis group were 3.87% (6/155) and 5.45% (3/55),51.22% (42/82)and 38.71% (12/31),respectively (P=0.235and 0.618).(3) Selective feticide was performed on 18 cases after prenatal diagnosis.Fifteen cases had survival neonates,two cases suffered from spontaneous abortion,and two cases had preterm labor with neonatal death.Conclusions (1) Invasive prenatal diagnostic procedures are effective and feasible in twins.Amniocentesis is a relative safer and simpler alternative to cordocentesis,which demanding higher skill and carrying higher fetal loss rate.(2) Mid-trimester selective feticide after prenatal diagnosis appears safety.Before the procedure,the chorionicity and fetal condition should be considered,in order to choose suitable feticide procedures.