This report presents the prevalence of mental and substance use disorders around the world discussing the impact of geographical, sociodemographic, and income characteristics on national epidemiological differences. We analysed data from the Institute of Health Metrics and Evaluation database published in 2019. The global prevalence of mental disorders was 13.0%, with higher prevalence of anxiety disorders rate (4.1%), followed by depressive disorders (3.8%, including major depressive disorder 2.49% and dysthymia 1.35%), intellectual disability (1.5%), ADHD (1.1%), conduct disorders (0.5%), bipolar disorders (0.5%), autism spectrum disorder s (0.4%), schizophrenia (0.3%), and eating disorders (0.2%, including bulimia nervosa 0.13% and anorexia nervosa 0.05%). The worldwide prevalence of substance-use disorders was 2.2%, not surprisingly, with higher prevalence of alcohol-use disorders (1.5%) than other drug-use disorders (0.8% total including: cannabis 0.32%; opioid 0.29%, amphetamine 0.10%; cocaine 0.06%). In general, high-income countries reported higher levels of mental and substance use disorders, with the exceptions of conduct and depressive disorders (no significant differences were found among low- and high-income countries), and intellectual disability (with higher prevalence in low-income countries). In regions of the America's prevalence rates of mental and substance use disorders were higher than in Europe. Western Pacific countries reported high levels of schizophrenia, and depressive disorders were highly prevalent in Africa as well as in the Americas. Intellectual disability reported higher rates in Eastern Mediterranean and South-East Asia. We discuss the cross-cultural variations in mental health expenditure and literacy as well as stigma-related factors and some of the environmental risk factors possibly related to these prevalence differences.