Unidirectional valves in internal jugulair vein have been known since the 16th century. These valves are bicuspid, semilunar or tricuspid. Their functions and importance are controversial. Since we saw that this subject has not been emphasised much in the literature, in our work we aimed to determine the length and diameters of jugular veins and localisation and type of valves in 6 human cadavers. Bicuspid valves and semilunar valves were determined in 5 and 6 of internal jugular veins respectively. One cadaver did not have a valve in his left internal jugular vein. Some cadavers had different types of valves in their right and left right internal jugular veins. These valves might cause an increase in pressure in the internal jugular veins and lead to a drop in cerebral perfusion pressure in head traumas. They may cause difficulties in catheterisation during central venous interventions and lead to damaging of veins. For this reason, these valves must be taken into consideration during central venous interventions.

Keywords :