This paper reports on the alignment between mouse and human anatomies, a critical resource for comparative science as diseases in mice are used as mod-els of human disease. The two ontologies under investigation are the NCI Thesaurus (human anatomy) and the Adult Mouse Anatomical Dictionary, each comprising about 2500 anatomical concepts. This study compares two approaches to aligning ontologies. One is fully automatic, based on a combination of lexical and structural similarity; the other is manual. The resulting mappings were evaluated by an expert. 715 and 781 mappings were identified by each method respectively, of which 639 are common to both and all valid. The applications of the map-ping are discussed from the perspective of biology and from that of ontology.