Background: Body weight dissatisfaction is a common problem in many modern societies and it appears to have grown over time. This study examined the prevalence and predictors of body weight dissatisfaction among 18- to 79-year-old Icelanders. The distribution of body weight dissatisfaction according to the WHO body mass index criteria for underweight, normal weight, overweight and obesity was also assessed. METHODS: The study was based on 5832 participants in the cross-sectional survey 'Health and Well-Being of Icelanders', administered by the Public Health Institute in Iceland in the fall of 2007. RESULTS: Around 43% of adult Icelanders are dissatisfied with their own body weight (50% of females; 35% of males) and 72% believe they need to lose weight (80% of females; 63% of males). Despite being in normal range according to the WHO-based BMI criteria, 64% of females in that category believe they need to lose weight. Multivariate results show that indicators of socio-economic status (SES) are not significantly associated with body weight dissatisfaction among females, while among males, those with university education are more often dissatisfied than those with secondary education (OR?=?1.5, P?