A randomized controlled trial (RCT) is a planned and controlled experiment. It is also a prospective study in which one or more interventions are assigned to human participants in order to assess the effects on health outcomes, such as the efficacy and safety of treatments and interventions for different diseases. Different outcomes, whether clinical, patient-related or economic, can be measured in RCTs. An outcome is a clinical, medical, surgical or any other event that seeks to measure the effectiveness and safety of the treatment or intervention to be evaluated in an RCT. The choice of one or more outcomes depends on the nature of the study and the question to be answered. Likewise, the use of a wide range of outcomes tends to be more informative than the measure of one alone. Therefore, it is important to recognize each of these to define their correct implementation in the field of clinical research. This study aims to describe the different types of outcomes, which are classified into nine categories: 1. Efficacy and safety; 2. Primary, coprimary, secondary and tertiary; 3. Simple and compound; 4. Positive and negative; 5. Clinically significant and subrogated; 6. Objective and subjective; 7. Single, repeated measures and counts (events); 8. Dichotomous and continuous; and 9. Fixed time and calendar time.