In a longitudinal cohort study, organizational climate and long-term effects of exposure to nasty teasing (aggression) at work were investigated. The baseline consisted of a representative sample of Danish employees in 1995 with a response rate of 80% (N = 5,652). Of these, 4,647 participated in the follow-up in 2000 (response rate 84%). In 1995, 6.3% were subjected to nasty teasing with no significant gender difference. At baseline, we found significant associations among nasty teasing, a negative organizational climate, and psychological health effects. In the follow-up analyses, associations were found between exposure to nasty teasing at baseline and psychological health problems at follow-up, even when controlled for organizational climate and psychological health at baseline and nasty teasing at follow-up. Stratified for gender, the follow-up associations were significant for women but not for men. Low coworker support and conflicts at baseline and teasing at follow-up mediated the effects on men. Key words: bullying, fatigue, gender differences, longitudinal study, mental health, teasing