The article addresses the problem of three types of significance of research results: statistical, practical and clinical significance. These issues are treated as chronological sequences in the evolution of how results of clinical research have been reported. For a long time, statistical significance was the only way of reporting research results. This method was subject to severe criticism showing that estimating the probability of results to be obtained by chance is not satisfactory from a clinically point of view. Statistical significance was followed by practical significance reporting, translated into size effect. Even though this change is a step forward, effect size says nothing about whether the intervention makes a real difference in the everyday life of the clients, or others whom the client interacts with. Thus, in recent years, the concept of clinical significance has been increasingly emphasized and operationalized most frequently by the quality of life, improvement in symptom level (improvement criteria), transition of patients from the dysfunctional to the functional distribution (recovery criteria) or a combination of them. Although this concept has also been subject to criticism, it has survived the debate and satisfies the set of criteria by which clinical research results are judged.