Gd-DTPA-dimeglumine is a new contrast agent for magnetic resonance imaging. Its safety and efficacy in man were evaluated in 20 volunteers and 60 patients. For determination of tolerance of Gd-DTPA, blood and urine samples were taken and blood pressure, pulse rate, and ECG were recorded before and after injection. The results of these analyses showed no clinically relevant changes. In MR imaging of intracranial lesions Gd-DTPA serves as an indicator of function or disfunction of the blood-brain-barrier, because its pharmacokinetic behavior is very similar to that of urographic iodinated contrast media used now for X-ray CT. And so by using Gd-DTPA it is possible to differentiate between neoplastic tissue and perifocal edema, to determine the extension of tumor infiltration, and to detect tumor recurrence.