The case reported consists of thrombosis of the left internal jugular vein occurring on the 22nd week of amenorrhea of a pregnancy achieved by IVF. No etiological factor other than biochemical ovarian hyperstimulation was found. Maternal outcome was positive but intrauterine fetal death occurred 7 weeks later at 29 weeks of amenorrhea. The late occurrence of this thrombosis after ovarian hyperstimulation need to be stressed.