Background: Few studies have explored both food behaviour and physical activity in an environmental context. Most research in this area has focused on adults; the aim of the present study was to describe perceptions of the environment, diet, physical activity and sedentary behaviour patterns in 16-20 year olds in full-time education (Newcastle, UK). Methods: Participants (n = 73) recruited from a college and sixth-form college completed a UK version of the Youth Neighbourhood Environment Walkability Survey, which included measures of sedentary behaviour. A validated food frequency questionnaire was completed and a factor applied to produce an estimated mean daily frequency of intake of each item, which was converted to nutrient intakes. A rank for Index of Multiple Deprivation (IMD) was assigned to their home postcode. Analysis explored associations between sedentary behaviours and nutrient intake. Results: In this descriptive cross-sectional study, most participants reported being physically active for at least 1 h day-1 on 3-4 (n = 28) or 5-7 days (n = 31). There were no significant differences in nutrient intake according to sample quartile IMD position. Sedentary behaviours were significantly associated with less healthy eating patterns. Higher total energy (P = 0.02), higher fat (P = 0.005), percentage energy from fat (P = 0.035) and lower carbohydrate intakes (P = 0.004) were significantly associated with more time spent watching DVDs at the weekend. Coclusions: This combination of sedentary behaviour and less healthy eating patterns has important implications for long-term health (e.g. the tracking of being overweight and obesity from adolescence into adulthood). Understanding behaviour relationships is an important step in developing interventions in this age group.