In neurosurgery, loca lisa tion of deepbra in structures isa crucia issue, which c a beaqB71 ed bya 3-dimensiona bra: a tlafiTk Our goa is to build such a ala by fusing histologica d aa witha 3D MR ima ge of the sa me subject. This requires two steps: firsta 2D rea lignment of the histologica l sections in order to obta ina three-dimensiona l block, thena 3D registra tion between this reconstructed blocka nd the MR imaHT Both stepsaq baqk on the sa e robust registr a iona lgorithm.