The present study investigated personality dimensions by means of the Temperament and Character Inventory (TCI) in subjects with social phobia with or without a co-existing avoidant personality disorder. Thirty-one individuals with social phobia were recruited through advertisement and diagnosed with the Structured Clinical Interview for DSM-IV I and II psychiatric disorders. Comorbid Axis I psychiatric disorders were diagnosed in 29% of the cases. Co-occurring personality disorders were present in 55.8% of the cases, and avoidant personality disorder in 48.4%. The social phobia subjects, as compared to healthy controls of the same age, scored significantly higher in the TCI dimension measuring Harm avoidance but significantly lower in Persistence, Self-directedness, Cooperativeness and Self-transcendence. Presence of avoidant personality disorders in the social phobia subjects was associated with significantly higher Harm avoidance, particularly on the subscale Shyness with strangers. In conclusion, individuals with social phobia were characterized by high comorbidity of avoidant personality disorder and deviations in TCI personality dimensions. Enhanced Harm avoidance was the most prominent personality trait. The observed deviations in TCI dimensions were primarily related to the social phobia itself and not to the presence of concurrent personality disorders.