Introduction: The purpose of this study was to estimate the prevalence and identify factors associated with simultaneous risk factors occurrence (clustering) for chronic diseases among adults. Methods: A cross-sectional population-based study was carried out with 1977 adults in Sousse, Tunisia. The simultaneous occurrence of tobacco smoking, physical inactivity, inadequate or unhealthy diet, obesity, and high blood pressure was assessed. The independent variables were demographic and socioeconomic characteristics. Results: Overall, 61% of Tunisian adults had two or more unhealthy risk factors compared to only 11% with none of the five risk factors. Prevalence of risk factors was greater in older subjects, females, married, with lower education, unemployed, and those with high socioeconomic status. Risk factors clustered in multiple combinations. The simultaneous presence of all risk factors was 40% higher of what would be expected by combining the individual prevalence of these risk factors. Physical inactivity, unhealthy diet, obesity, and high blood pressure showed the strongest association among the clusters. Conclusion: Multiple chronic disease risk factors are frequent and occur more often than expected among Tunisian adults, especially women, married, older subjects, with low education and high socioeconomic level. Information on high risk groups will help in planning future preventive strategies.