Abstract: Objective: This review is a narrative synthesis of the RCTs which studied the efficacy of using diagnostic tests to reassure patients.Methods: We searched for RCTs that examined the level of reassurance after diagnostic testing in outpatients. We used PubMed, Psychinfo, Cochrane Central, Ongoing Trials Database and Scopus.Results: We found 5 randomized controlled trials that included 1544 patients. The trials used different diagnostic tests (ECG, radiography of lumbar spine, MR brain scan, laboratory tests, MR of lumbar spine) for different complaints (e.g. chest pain, low back pain and headache). Four out of 5 RCTs did not find a significant reassuring value of the diagnostic tests. One study reported a reassuring effect at 3 months which had disappeared after one year.Conclusion: Despite the sparse and heterogeneous studies, the results point in the direction of diagnostic tests making hardly any contribution to the level of reassurance. We recommend further studies on the use of diagnostic tests and other strategies to reassure the patient.Practice implications: A clear explanation and watchful waiting can make additional diagnostic testing unnecessary. If diagnostic tests are used, it is important to provide adequate pre-test information about normal test results.