Fetal risk related to cordocentesis has been analyzed on a series of 222 ultrasound-guided fetal blood samplings for prenatal diagnosis of fetal diseases during the second trimester of pregnancy. Affected and malformed fetuses were excluded. Seven intrauterine deaths (3.2%) and 2 spontaneous abortions (0.9%) were observed. These figures proved higher than those observed in non-homogeneous series which consider the second and third trimester altogether. The fetal risk was significantly correlated with gestational age (less than 18 weeks 7.6% vs greater than 18 weeks 0.7% p = .02) and duration of the procedure (greater than 10'11.4% vs = less than 10'0.9% p = .0029). The number of abdominal insertions resulted in different death rates (greater than 1 ins. = 6.5% vs 1 ins. = 1.4%). It is likely that different developmental, anatomical and neurovegetative mechanism play a significant role in the risk rate found in the second trimester cordocentesis. These findings and the specific risk factors observed within the different technical conditions reported, must be taken into consideration for prenatal counseling.