BACKGROUND: To determine if the common Pro12Ala polymorphism (rs1801282) of the peroxisome proliferator-activated receptor (PPARG) gene is associated with the metabolic syndrome (MetS) or with its individual components in middle-aged Swedish individuals. METHODS: MetS was defined according to the National Cholesterol Education Program/Adult Panel III (NCEP/ATP III), the International Diabetes Federation (IDF) and the European Group for the Study of Insulin Resistance (EGIR) criteria in a population-based sample of nearly 5000 subjects participating in the Malmö Diet and Cancer-cardiovascular arm. RESULTS: Of the subjects included in the analysis, 21.8, 29.4 and 20.4% had MetS according to the NCEP/ATP III, IDF and EGIR (only in subjects without diabetes) definitions, respectively. The Pro12Ala was not associated with MetS or with its individual components. These results were similar when patients with diabetes were excluded. Hypertensive and obese ala-carriers had lower fasting glucose and hypertensive ala-carriers also had lower level triglycerides (P