This study adds to the very few published reports of the structure of the Tridimensional Personality Questionnaire (TPQ) at both the item and subscale levels. The TPQ was completed by 897 students from Universities within Edinburgh. Exploratory factor analysis was run on the items and the 12 subscales as described by Cloninger, Przybeck, and Svrakic (1991). Harm Avoidance showed high internal consistency both for the whole scale and the subscales; however, this was not the case for Reward Dependence and Novelty Seeking. A three factor solution was extracted from analysis at the scale level which gives support to Cloninger's model. However, when analysis was carried out at the item level, three and four factor solutions were extracted with only one factor, that of Harm Avoidance, resembling Cloninger's model. The four factors extracted were provisionally named Harm Avoidance, Conscientiousness, Sociability and Impulsiveness. These more closely resemble factors from the Five Factor Model (Costa & McCrae, 1992) and Eysenck's three factor model (Eysenck, Eysenck, & Barrett, 1985) than Cloninger's theory. It may be necessary to adapt Cloninger's model for a British sample, and more generally to question the psychometric structure of the TPQ. © 2003 Elsevier Ltd. All rights reserved.