Persistent organochlorine pollutants (POPs), such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), dichloro diphenyl trichloroethane (DDT) and its major metabolite 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p' -DDE) have been associated with type 2 diabetes mellitus (T2DM) in recent epidemiological studies. We have analysed 2,2',4,4',5,5' -hexachlorobiphenyl (CB-153) and p,p'-DDE in 544 serum-samples from Swedish women with a median age of 50 years. The participants were asked if they had diabetes and if so, what type of diabetes, years since diagnosis and what kind of treatment they had. Associations between exposure and T2DM were analysed by logistic regression. Moreover, trends of T2DM prevalence were tested with Jonckheere-Terpstrá test. Sixteen of the 544 women (3%) had diabetes, of which 15 were classified as T2DM. There was a significant association with T2DM for both CB-153 (an increase of 100 ng/g lipid corresponded to an odds ratio [OR] of 1. 6, 95% confidence interval [CI] 1. 0, 2. 7) and p,p9-DDE (OR 1. 3, 95%CI 1. 1, 1. 6). In addition, significant positive trends between quartiles of CB-153 and T2DM (P 5 0. 004) and p,p9-DDE and T2DM (P 5 0. 002) were observed. The study shows an association between POP serum concentrations and an increased prevalence of T2DM.