The relationship between Kretschmer's temperament types and Jung's psychological types of introversion and extraversion was investigated. Undergraduates, 304 in total, completed the common items of Type-Trait Integrated Questionnaire and Jung's Psychological Types Scale. Results indicated that cyclothymic temperament (syntonic) scores correlated positively with extraversion-introversion scores, and that schizothymic temperament scores correlated negatively with extraversion-introversion scores. In addition, there were significantly more extraverted types than introverted types in cyclothymic personality type, and there were significantly more introverted types than extraverted types in schizothymic personality type. These findings supported previous theoretical studies.