The aim of this study was to assess the association between temperament and metabolic syndrome markers. Cloninger's Temperament and Character Inventory and clinical examination were carried out in 1997 in the Northern Finland Birth Cohort 1966 (N = 4364 respondents). Novelty seeking was positively associated with waist circumference in both genders. Systolic blood pressure was highest in men with high harm avoidance and low persistence scores and lowest in women with high reward dependence and high persistence scores. Childhood socio-economic status did not confound these associations. Smoking and alcohol consumption were associated with higher novelty seeking. Our results suggest that temperament is associated with metabolic syndrome markers and this association may be partly mediated by lifestyle factors and socio-economic status in adulthood.