Rationale and Objectives: Gd-DTPA is a well-characterized, safe contrast agent frequently used in magnetic resonance imaging (MRI) of the central nervous system. The purpose of this double-blind, comparative MRI study of brain, spine, trunk, and limbs was to evaluate the safety and efficacy of Gd-DOTA versus Gd-DTPA in a large number of patients (n = 1038)., Methods: T1-weighted MRI was performed before contrast and after the administration of Gd-DOTA or Gd-DTPA (0.1 mmol/kg). The MR images were scored for image quality, and the diagnostic efficacy also was assessed. Patients were questioned 1 hour after injection, and adverse reactions were recorded., Results: Image quality of the T1-weighted MR images without contrast was good or excellent in 89.7% and 91.7% of the Gd-DOTA and Gd-DTPA groups, respectively (P > 0.2). After contrast, 85.8% (Gd-DOTA) and 88.2% (Gd-DTPA) of the T1-weighted MR images were of good to excellent image quality (P > 0.2), significantly less than before contrast (P < 0.001, both groups). In 82.3% of the Gd-DOTA group and 83.5% of the Gd-DTPA group (P > 0.2), the information obtained was more accurate with the administration of contrast agents. In 82.4% (Gd-DTPA) and 81.9% (Gd-DOTA) of patients, confirmation was obtained of diagnosis without contrast, whereas in 17.0% and 17.3% of patients, therapy was modified as a result of the use of contrast (P > 0.2, both groups). The MRI investigation was reported as abnormal in 58.3% (Gd-DOTA) and 59.6% of patients (Gd-DTPA), indicating a similar prevalence of disease in each group. Patients responded that 97.8% (Gd-DOTA) and 98.5% (Gd-DTPA) of the investigations went well and adverse reactions, none of them serious, were encountered in 0.97% of Gd-DOTA and 0.77% of Gd-DTPA groups (P > 0.2, both groups)., Conclusion: This double-blind, randomized, clinical trial comparing Gd-DTPA and Gd-DOTA revealed no serious adverse reactions, whereas minor adverse reactions were encountered in fewer than 1% of patients. Gd-DOTA is as safe a contrast agent as Gd-DTPA and has similar diagnostic efficacy.