The 3-dimensional shape of the human utricular macula and its orientation in the skull are quantitated in this report, which is one of a series. The semicircular canals and utricular macula were reconstructed in 3 dimensions on a computer from 3 human temporal bones. The 238 to 279 triangles in the entire area of the utricular macula were made by drawing lines between 2 adjacent points every 200-microm width of the utricular macula in each section. We calculated the angles between each triangle and each estimated standard axis in the skull. This study provides standard data regarding the 3-dimensional morphological aspects of the utricular macula for further investigation of the function of the utriculus. We determined that the 3-dimensional shape of the utricular macula was not a plane, but was a curved surface like that of an ellipsoid. We believe this shape is necessary for the utricular macula to detect wide-range linear acceleration.