Objective: We aimed to investigate whether the Prognos (R) device might be a useful tool in the diagnosis of disorders suspected to be due to dental amalgam fillings. Participants and Methods: A diagnostic case-control study was performed in 27 patients who complained about health problems attributed to amalgam ( cases), 27 healthy volunteers with amalgam fillings ( controls I), and 27 healthy amalgam-free volunteers ( controls II). All participants were tested before and after application of 300 mg DMPS (2.3-dimercapto-1-propanesulfonic acid) with Prognos, a diagnostic device for the energetic measurement of Traditional Chinese Medicine meridians. In addition, mercury was measured in blood, urine, and saliva, and a lymphocyte transformation test (LTT) was performed. Results: Diagnoses derived from the first and second Prognos testing did not agree above chance (Cohen's Kappa = -0.11, 95% confidence interval -0.33 to 0.10; p = 0.30). Agreement for secondary outcome measures was poor, too. Prognos measurements did not differ between cases and controls. Correlations with measurements in urine, blood and saliva were low. Conclusion: In this study Prognos could not be shown to be a useful tool in the diagnosis of disorders suspected to be due to dental amalgam fillings.