OBJECTIVES: To examine associations of total sitting time, TV-viewing and leisure-time computer use with cardiometabolic risk biomarkers in adults. DESIGN: Population based cross-sectional study. METHODS: Waist circumference, BMI, total cholesterol, HDL cholesterol, blood pressure, non-fasting glucose, gamma glutamyltransferase (GGT) and triglycerides were measured in 48,882 adults aged 20 years or older from the Nord-Trøndelag Health Study 2006-2008 (HUNT3). Adjusted multiple regression models were used to test for associations between these biomarkers and self-reported total sitting time, TV-viewing and leisure-time computer use in the whole sample and by cardiometabolic disease status sub-groups. RESULTS: In the whole sample, reporting total sitting time ≥10h/day was associated with poorer BMI, waist circumference, total cholesterol, HDL cholesterol, diastolic blood pressure, systolic blood pressure, non-fasting glucose, GGT and triglyceride levels compared to those reporting total sitting time <4h/day (all p<0.05). TV-viewing ≥4h/day was associated with poorer BMI, waist circumference, total cholesterol, HDL cholesterol, systolic blood pressure, GGT and triglycerides compared to TV-viewing <1h/day (all p<0.05). Leisure-time computer use ≥1h/day was associated with poorer BMI, total cholesterol, diastolic blood pressure, GGT and triglycerides compared with those reporting no leisure-time computing. Sub-group analyses by cardiometabolic disease status showed similar patterns in participants free of cardiometabolic disease, while similar albeit non-significant patterns were observed in those with cardiometabolic disease. CONCLUSIONS: Total sitting time, TV-viewing and leisure-time computer use are associated with poorer cardiometabolic risk profiles in adults. Reducing sedentary behaviour throughout the day and limiting TV-viewing and leisure-time computer use may have health benefits.