Objectives: To look at trends in generalised (body mass index (BMI) $30 kg m -2 ) and abdominal (waist circumference (WC) .102 cm in men, .88 cm in women) obesity among adults between 1993 and 2003, and to evaluate their association with diabetes, hypertension and hypertension-diabetes co-morbidity (HDC) in England. Design: Analyses of nationally representative cross-sectional population surveys, the Health Survey for England (HSE). Subjects: Non-institutionalised men and women aged $35 years. Measurements: Interviewer-administered questionnaire (sociodemographic information, risk factors, doctor-diagnosed diabetes), measurements of height and weight to calculate BMI. WC and blood pressure measurements were taken by trained nurses. Results: Generalised obesity increased among men from 15.8% in 1993 to 26.3% in 2003, and among women from 19.3% to 25.8%. Abdominal obesity also increased in both sexes (men: 26.2% in 1993 to 39.0% in 2003; women: 32.4% to 47.0%). In 1994, 1998 and 2003, generalised and abdominal obesity were independently associated with risk of hypertension, diabetes and HDC. The odds of diabetes associated with generalised obesity in 1994, 1998 and 2003 were 1.62, 2.26 and 2.62, respectively, in women and 1.24, 1.82 and 2.10, respectively, in men. Similar differences were observed for hypertension and HDC. Men and women with abdominal obesity also showed a higher risk for diabetes, hypertension and HDC than those with a normal WC. Conclusions: If current trends in obesity continue then the risk of related morbidities may also increase. This will impact on cardiovascular disease morbidity and mortality, with cost implications for the health service. Therefore there is an urgent need to control the epidemic of obesity.