To evaluate the psychometric characteristics of the Swedish version of the Junior Temperament and Character Inventory (J-TCI), it was sent to parents of 9- and 12-yr.-old twins in Sweden. The final number of responders was 196 parents who rated 92 female and 104 male twin pairs. The inventory of one twin, randomly chosen from each pair, was included in the analyses. Reward Dependence, Persistence, and Cooperativeness were scored higher in girls; Novelty Seeking was higher in the 9-yr.-olds and Persistence in the 12-yr.-olds. Pearson's correlations showed that some dimensions were not statistically independent from each other, even if the covariance was moderate. Internal consistency (Cronbach's alpha) was satisfactory for Harm Avoidance, Novelty Seeking, Self-Directedness, and Cooperativeness (.68-.81), while it was lower in those dimensions that had fewer items. The Swedish parent version of the J-TCI shared about the same psychometric characteristics as found in international samples.