A morphometric analysis of 43 human maculae utriculi is presented. Individual data on the shape, total area and relative area of the pars interna are given. In addition, the sensitivity of the entire macula to shear stimuli in different directions was estimated. The mean area of 39 maculae from adults and children was 4.30 +/- 0.30 (SD) mm(2). The pars interna was slightly but significantly smaller than the pars externa. The interindividual variability was larger for the shape of the macula than for the total area and the percentage of the pars interna. The estimated responsiveness of the macula was largest for shear directed anteromedially and smallest for shear directed posteriorly. The data are discussed taking into consideration clinical findings on patients with unilateral loss of otolith function.