The DSM-III employs a categorical model for the classification of personality disorders. A dimensional model provides certain advantages, but there has not yet been an empiric attempt to identify an optimal set of dimensions. We systematically assessed the presence of each of the symptoms for the personality disorders in 84 patients. The number of symptoms of each of the personality disorders possessed by each patient was correlated across patients, and the correlations were subjected to a multidimensional scaling program. A three-dimensional solution was compared with the placements of the personality disorders predicted by dimensions published previously.