594 patients with Hodgkin's disease were treated from 1983 to 1993 at the Department of Radiotherapy and Institute of Hematology, "La Sapienza" University, Rome, Italy. 385 patients presented mediastinal involvement; CT and/or chest radiography showed residual mediastinal masses in 96 of them (25%). In this study we included only the patients treated after 1986; they were examined with MRI of the chest (24 patients) and 67Gallium scintigraphy of the mediastinum (44 patients) with or without SPECT, combined with high-dose 67Ga in some cases. Eighteen patients underwent both MRI and 67Gallium scintigraphy. MR accuracy, sensitivity and specificity were respectively 75%, 86% and 86%; gallium scintigraphy had 86%, 77% and 93%. These data were confirmed by the results fo the subgroup of 18 patients submitted to both exams; MRI had higher sensitivity (80% vs. 75%) and lower specificity and accuracy (83% vs. 80% and 72% vs. 67, respectively) than 67Gallium scintigraphy. The predictive value of MR-scintigraphy agreement is high: indeed, no false negatives or false positives were observed when MR and scintigraphy results were in agreement.