Eleven patients with intracranial tumors were investigated with MR imaging at different dose levels of gadolinium-DTPA to determine a safe and effective dose for imaging intracranial tumors. The patients were divided into two groups. Baseline spin-echo images were obtained with a repetition time of 800 msec and an echo time of 35 msec, and a total of 0.1 mmol of gadolinium-DTPA/kg (six patients) or 0.2 mmol gadolinium-DTPA/kg (five patients) was injected according to a fractionated incremental dose regime (0.025, 0.025, and 0.05 mmol/kg and 0.05, 0.05, and 0.1 mmol/kg, respectively). Postcontrast MR was performed after each injection. In group 1 the best visualization was achieved after the third injection in four cases. In one glioblastoma and in a pituitary adenoma tumor margins were well defined at lower dose levels. In group 2, with five patients, the total dose of 0.2 mmol of gadolinium-DTPA/kg (0.05, 0.05, and 0.1) significantly improved tumor visualization after the third injection in only one patient with multiple metastases. No short-term side effects were encountered. In a range of parameters measured in both serum and whole blood, slight transient elevation of serum iron levels was the only appreciable change. As a result of our investigation we conclude that 0.1 mmol of gadolinium-DTPA/kg is a safe and suitable dose for brain-tumor imaging. In selected cases of 0.2 mmol/kg may increase the diagnostic yield.