OBJECTIVES: To examine the relationship between time since immigration and excess body weight. METHODS: Secondary data analysis of a cross-sectional survey of 19,600 Canadians. RESULTS: The prevalence of excess weight (BMI > 25) increases with time since immigration for both men and women. After controlling for birthplace, socio-demographic, lifestyle and health correlates, only female immigrants (less than five years) are significantly less likely to have BMI scores greater than 25 kg/m2 compared to those born in Canada. Stratified analyses, however, revealed similar findings for Asian men who had immigrated less than five years prior to the survey. DISCUSSION: Our results suggest that length of time since immigration is an important risk factor for excess weight. Further research with longitudinal data, more reliable measures of ethnicity and anthropometric measures of weight are required to confirm these initial findings.