Aims: Increased intraarticular hip joint pressure has been considered a pathomechanism in femoral head necrosis. The aim of this study was to investigate histopathological femoral head changes in an immature big animal model of arterial hip joint tamponade. Methods: Out of a total of 15 domestic pigs, 11 animals were randomly chosen to undergo 6h unilateral hip joint tamponade at an intraarticular pressure of 250mmHg while 4 animals underwent a unilateral sham operation serving as controls. 4h after the end of hip joint tamponade, the animals were killed with potassium chloride, the femoral heads were excised, and þxed in Schafferñs solution for undecalciþed Goldnerñs, alcianblue-PAS, Krutsay, methyl green pyronine, toluidin blue O, and standard Giemsa staining. Results: A great number of congested sinus and vessels of the terminal vascular system showed inclusions of blood cells dominantly in the tamponaded hip side. Congestion also be documented by dilated sinus with deformed blood cells. Bone remodeling of normal osteoblast and osteoclastic lacuna activity was noted in all trabeculae. None of the known signs of osteonecrosis were found. Conclusions: Our acute histological study in immature pigs shows the early microcirculatory disturbances which may precede femoral head necrosis. Future research is needed to investigate histologic changes after a longer time interval following hip joint tamponade, and into the duration of the joint tamponade.