ObjectivesComprehensively measure the trends in health disparities by sociodemographic strata in terms of exposure to lifestyle and metabolic risks, and prevalence and mortality of non-communicable diseases (NCDs) during the last 20 years in Belgium.DesignCross-sectional analysis of periodic national-representative health interview surveys and vital statistics.SettingPopulation-based study of adult residents in Belgium between 1997 and 2018.ParticipantsAdults aged 25–84 years and resident in Belgium in the years 1997 (7256 adults), 2001 (8665), 2004 (9054), 2008 (7343), 2013 (7704) and 2018 (8358).Main outcome measureAge-standardised prevalence rates of modifiable lifestyle risks (poor diet, smoking, excessive alcohol use and leisure-time physical inactivity), metabolic risks (high body mass index (BMI), blood pressure and cholesterol levels) and major NCDs (type 2 diabetes mellitus (T2DM), cardiovascular diseases (CVDs), cancer, asthma and chronic obstructive pulmonary disease (COPD)), with their relative health disparities across strata by age, sex, region of residence, nationality, education and income level, and according to high versus low engagement in the four lifestyle risks, calculated from a survey-weighted age-adjusted logistic regression.ResultsGreater avoidable disparities were observed between extremes of education and income strata. The most marked disparities were found for exposure to lifestyle risks (except excessive alcohol use), prevalence of high BMI as well as T2DM, asthma and COPD, with disparities of daily smoking and COPD worsening over time. Still, NCD-specific mortality rates were significantly higher among men (except asthma), residents of Wallonia and Brussels (except cerebrovascular disease), and among the native Belgians (except T2DM and asthma). High engagement in lifestyle risks was generally observed for men, residents of the region Wallonia, and among lower education and income strata. This subgroup (20%) had a worse health profile as compared with those who had a low-risk lifestyle (25%), shown by prevalence ratios varying between 1.1 and 1.6 for metabolic risks, and between 1.8 and 3.7 for CVD, asthma and COPD.ConclusionsImproving population health, including promoting greater health equity, requires approaches to be tailored to high-risk groups with actions tackling driving root causes of disparities seen by social factors and unhealthy lifestyle.