OBJECTIVE: Psychological factors may be important determinants of adherence to antihypertensive medication, as they have been repeatedly found to be associated with an increased risk of hypertension, coronary heart disease, and health-damaging behaviours. We examined the importance of several psychological attributes (sense of coherence, optimism, pessimism, hostility, anxiety) with regard to antihypertensive medication adherence assessed by pharmacy refill records. METHODS: A total of 1021 hypertensive participants, aged 26-63 years, who were employees in eight towns and 12 hospitals in Finland were included in the analyses. RESULTS: We found 60% of patients to be totally adherent, 36% partially adherent, and 4% totally nonadherent. Multinomial regression analyses revealed high sense of coherence to be associated with lower odds of being totally nonadherent in contrast of being totally adherent (odds ratio=0.55; 95% confidence interval: 0.31-0.96). This association was independent of factors that influenced adherence to antihypertensive medication, such as sociodemographic characteristics, health-related behaviours, self-reported medical history of doctor-diagnosed comorbidity, and anteriority of hypertension status. The association was not specific to certain types of antihypertensive drugs. CONCLUSION: High sense of coherence may influence antihypertensive medication-adherence behaviour. Aspects characterizing this psychological attribute, such as knowledge (comprehensibility), capacity (manageability), and motivation (meaningfulness) may be important determinants of adherence behaviour for asymptomatic illnesses, such as hypertension, in which patients often do not feel or perceive the immediate consequences of skipping medication doses.