This is a qualitative comparative case study which examines the impact of Marxism on Cuba’s social system. The study examines the influence of the theory during the periods 1959-1969 where Fidel Castro was president and 2018-2023 during Miguel Díaz-Canal's rule. It examines Marxism's impact on Cuba's social system through the perspectives of political institutions, economic indicators, and social indicators. Thenceforth, the theory is applied to these to indicate the impact of the theory on Cuba’s social system. The purpose of the study is to analyze the impact of Marxism on Cuba's social system using the three perspectives during the two periods, and examine if the impact of the theory has developed. The research questions are: “How much impact did Marxism have on the social system in Cuba in 1959–1969, during Fidel Castro's first year as ruler?”, “How much impact does Marxism have on the social system in Cuba in 2018-2023, under the rule of Miguel Díaz-Canel?” and “How has the impact of Marxism on the social system in Cuba changed in relation to these periods?” This study has proven that Marxism has had a strong impact on Cuba's social system during Castro's first years as president. Furthermore, Marxism still has a strong impact under the rule of Miguel Díaz-Canal despite that new reforms have been introduced that deviate from the fundamental ideas of the theory. This calls into question the future impact of Marxism on Cuba’s social system.