Aim:Based on previous qualitative studies, it was hypothesised that dissimilarities in beliefs about illness, which influence healthcare-seeking behaviour, exist between foreign- and native-born persons diagnosed with type 2 diabetes living in Sweden (in the following termed ‘Swedish-born’).Background:Beliefs about illness are individual, culturally related, based on knowledge, and guide health-related behaviour, and thus have an impact on health. The question is whether beliefs differ between foreign- and native-born persons diagnosed with type 2 diabetes. No previous comparative studies have been found on this. Based on previous qualitative studies, it was hypothesised that dissimilarities in beliefs about illness, which influence healthcare-seeking behaviour, exist between foreign- and native-born (Swedish) persons diagnosed with type 2 diabetes living in Sweden.Methods:Cross-sectional survey, 138 participants, comprising 69 foreign- and 69 Swedish-born persons aged 33–90 vs 48–91 years. Data were analysed with descriptive and analytic statistics.Findings:Beliefs about illness differed between foreign- and Swedish-born persons concerning causes of diabetes and healthcare-seeking behaviour. Foreign-born persons more often than Swedish-born persons reported uncertainty or lack of knowledge about whether heredity (67% vs 90%,P= 0.002) and pancreatic disease (40% vs 62%,P= 0.037) could cause diabetes. To a higher extent than Swedish-born persons, they reported that emotional stress and anxiety could cause the disease. Furthermore, they claimed they had sought care due to diabetes during the last 6 months to a higher extent than Swedish-born persons (30% vs 4%,P= 0.000).The findings confirmed that dissimilarities in beliefs about illness, including the causes of diabetes and healthcare-seeking behaviour, exist between foreign- and Swedish-born persons with type 2 diabetes.