Background The prevalence of overweight and obesity appears greater in persons with an intellectual disability (PwID) than those in the general population. This has been widely reported in the literature. Few studies have examined the nutritional intakes of PwID. The aim of this study is to describe the anthropometric status and the nutritional intakes in PwID. Methods Adults with an ID (16-64 years) were recruited from four ID service provider organisations, in the Republic of Ireland. Almost 2000 PwID were invited to participate in the study and 131 participated in one or more parts. The Survey on Lifestyle and Attitudes to Nutrition (SLAN) 2007 questionnaire was adapted for use in this population. Interviews were carried out face to face with PwID and family members. Weight, height and waist circumference measurements were obtained. Participants were invited to complete a four day food diary, over two week and two weekend days. Results The mean BMI of the overall study sample was 29.4kg/m2 ±6.1. The mean BMI of men was 28.8kg/m2 and the mean BMI of women was 30.2 kg/m2, with 2.4% of the sample underweight, 22.6% normal weight, 28.2% overweight and 46.8% obese. Having a diagnosis of Down’s syndrome (p=0.03) and greater fried food consumption (p=0.041) were associated with increasing BMI. Increasing waist circumference was associated with increasing severity of ID (p=0.04). Mean reported energy intakes were 2044kcal/day for men and 1684kcal/day for women. Mean energy intakes from sugar, fat and saturated fat are above maximum recommended intakes and few study participants met micronutrient RDAs. Conclusion This study highlights the alarming prevalence of overweight and obesity in PwID. While under reporting of nutritional intake is suspected in the study participants this study also highlights the poor diet quality of study participants. Key Words: intellectual disability, body mass index, obesity, diet, nutrition, associated factors