Subgroup analyzes are often used to evaluate the efficacy of drugs, technologies, or procedures in clinical trials. In practice, we then encounter several problems and errors in their interpretation. The article briefly summarizes the relevant statistical theory and, using the example of a specific oncological study, shows how the results of subgroup analyzes should be correctly presented in scientific publications. Finally, the situations that may arise when evaluating subgroups in clinical trials and interpreting them correctly are discussed.