The reliability and temporal stability of various individual differences and tolerance to shiftwork measures were evaluated. The subjects selected were 604 male, oil refinery workers, who worked in a 2:2:3 continuous three shift system with the morning hours from 0600 to 1400 hours (hr), the afternoon shift from 1400 to 2200hr, and the night shift from 2200 to 0600hr. The shifts rotated in the order mornings, afternoons, nights, followed by days off. Test batteries relating to individual differences and tolerance were administered. A subsample of 61 workers (29 very tolerant, and 32 very intolerant to shiftwork), was reexamined using the same questionnaires after 9yr. Questionnaires used were the Jenkins Activity Survey (JAS), Eysenck Personality Inventory, Morningness/Eveningness Questionnaire, Behavioral Arousal Questionnaire (BAQ), Circadian Type Questionnaire and Inventory, Way of Life Questionnaire, and the Health Information Questionnaire (HIQ) for Sleep Quality and Psychosomatic Digestive Complaints. Scoring was compared for 14 individual difference measures, and eight tolerance to shiftwork measures. Sleep periods during night, morning, and afternoon shifts, and on off days were also used as measures of tolerance to shiftwork. Results showed that the correlations between the scores obtained in the two test periods, which was a reflection of the stability of the measurements used over time, were quite high, particularly since there was a long lapse between the two tests. Of the individual difference measures, the dimension of vigorousness/languidness was less stable, and showed low correlations between the two test administrations. This, the JAS/Speed and Impatience, and BAQ/Flexibility of Behavior, and all other individual difference measures were temporally somewhat stable. Tolerance to shiftwork was also temporally somewhat stable with the exception of HIQ Respiratory Complaints and Digestive Problems. The authors conclude that once established, tolerance or intolerance to shiftwork is stable over time.