In the evaluation of multinodular goitre, finding a malignant neoplasia is often an unexpected result of the histological diagnosis. TRIMprob (Tissue Resonance Interaction Method Probe) is a portable system for non-invasive diagnosis, that utilises the different electromagnetic properties of healthy and pathological tissues, producing a low-power magnetic field that interacts with the molecular structure of tissues. The interference levels are detected by a receiver device and are elaborated with software in a graph consisting of 3 easily interpretable bands. The objective of our study was to assess the usefulness of the TRIMprob system in the preoperative diagnosis of carcinoma in patients with multinodular goitre. Over the period from January 2005 to March 2006 we used TRIMprob to screen 51 patients with a clinical diagnosis of multinodular goitre, later operated on by total thyroidectomy. We then compared the TRIMprob response with the histological diagnosis on the surgical specimen. The TRIMprob results suggested 46 cases compatible with non-malignant goitre and 5 suspected cancers. The final histological diagnosis confirmed these results with 46 cases of multinodular goitre and 5 papillary carcinomas. The sensitivity, specificity and diagnostic accuracy of the procedure were all 100%. On the basis of these preliminary results, TRIMprob seems to be a highly accurate method for the detection of suspected carcinomas in the context of multinodular goitre. If these results are confirmed, new prospects could be opened up in the diagnosis of thyroid diseases.