The value of the superparamagnetic contrast medium AMI-25 and its clinical acceptability was investigated in a phase-III-multicenter study. 18 patients with primary and secondary hepatic tumours were studied using T2- and T1-weighted spin-echo sequences, FATSAT sequences and FLASH-2-D-breathold sequences, both before and after intravenous application of AMI-25 (0.2 mmol GE/ml 15 mmol/kg KG in 100 ml 5% glucose infusion), using a 1.5 Tesla MRT (Magnetom 63 SP, Siemens). In 6 patients the MRT findings could be correlated with in vitro results within 30 minutes following surgical resection. In 8 patients a diagnosis of metastases was made. Amongst patients with primary liver tumours (FNH 6 cases, HCC 3 cases, adenomatosis 1 case) 3 of the 10 patients showed more lesions following the injection of contrast; similarly, in 4 patients of the 8 with secondary tumours contrast increased the number of visible lesions. The absence of contrast enhancement separated primary from secondary lesions. Amongst the patients with secondary liver tumours, in vitro correlation always showed more tumours than had been visualised whereas there was exact in vivo/in vitro correlation amongst patients with primary liver tumours.