How people perceive the healthiness of their diets may influence their receptivity to dietary recommendations, as those who perceived their diet as healthy are unlikely to change the way they eat. As many people optimistically assess the healthiness of their food choices, this may limit the effectiveness of future promotion campaigns ^{(Reference Miles and Scaife1)}. The aim of this study was to explore the relationship between perceived healthy eating behaviours (PHEB) and sociodemographic, lifestyle and dietary factors in Irish adults. This study was performed using data from the National Adult Nutrition Survey collected between 2008–2010 (n = 1219, male/female, 599/620). Food intake was assessed using a 4-day semi-weighed food diary. PHEB was assessed using an average of 6-items taken from previous studies (e.g., “Healthy eating is something I do frequently”). All items were measured on a 7-point Likert scale, ranging from 1 = strongly disagree to 7 = strongly agree. Multiple linear regressions were used to explore the influence of sociodemographic, lifestyle, and dietary factors on PHEB. Three models were explored: 1) sociodemographic and lifestyle, 2) nutrient and 3) food group. Under-reporters (n = 387) were defined as individuals with an energy intake to basal metabolic rate ratio of less than 1.1. Models 2 and 3 were run with and without under-reporters included. The standard criteria for statistical significance (P < 0.05) were adjusted for multiple comparisons using the Bonferroni correction. The sociodemographic and lifestyle model predicted 18.6% of the variation in PHEB. Women, older adults, people with lower BMI, non-smokers and those who took dietary supplements had significantly higher PHEB. When under-reporters were excluded, the nutrient and food group models explained 22.8% and 32.6% of the variation in PHEB, respectively. Total energy and sodium intakes were negatively associated with PHEB, and protein and fibre intakes were positively associated with PHEB. Out of the 31 food groups assessed, four (vegetable dishes, fruits, brown bread, pasta, rice and flours and fish, fish products and dishes) showed a significant positive association and four (chipped and processed potatoes, butter and hard fats, biscuits, alcoholic beverages, sugar-sweetened beverages) showed a significant negative association with PHEB. Similar relationships were observed when under-reporters were included. These findings corroborate previous research on Irish adults^{(Reference Hearty, McCarthy and Kearney2)} and indicate that women, older adults, people with a lower BMI and those with healthier lifestyles have higher PHEB. We also found that participants with higher PHEB tended to consume food and nutrients more aligned with dietary recommendations. This demonstrates a broad awareness of what constitutes a healthy diet and suggests efforts to improve nutrition knowledge may have limited success in changing food choices. Future healthy eating campaigns may benefit from addressing the broader influences of food choices^{(Reference Contento3)}, particularly among young men and those with less healthy lifestyles.