the posterior dislocation of the hip joint is a trauma that can undergo a large part of the population, which may compromise the sciatic nerve, causing serious problems in the life of the affected individual. knowledge of the anatomical relationship between the sciatic nerve and the posterior margin of the acetabulum will facilitate accurate diagnosis and early um this injury. in order to study the topographical relationship of the sciatic nerve with the posterior margin of the acetabulum and provide background for orthopedic anatomical in posterior dislocations of the hip were studied 40 lower limbs formolized human cadavers, adults of both sexes , located in the topographical anatomy laboratories of the universidade estadual de ciencias da saude, alagoas, brasil. in 19 limbs (47.7%) sciatic nerve passed directly over the posterior margin of the acetabulum and the remaining 21 (53.3%), the nerve passed distal to the acetabular margin, distance ranging from 6-49 mm. the results show the close relationship between the sciatic nerve and the acetabular margin, which increases the possibility of nerve injury in posterior dislocation of the hip.