Purpose : With the development of MR Imaging techniques, MRI and MR spectroseopy can be used to evaluatespecimens both in vivo and in vitro. For extracted tissue specimens we wished to obtain MR images which correlatedwell with images obtained in vive; the purpose of this study was to determine which fixatives and time intervalbest facilitated this objective. Materials and Methods: After in vivo MR imaging, sample tissues of liver, renalcortex and renal medulla were obtained from ten healthy rabbits. Each tissue sample was placed in 75% ethanol, 10%formalin, and 0.9% normal saline and MR scans of each sample were performed at 30 minutes, 11/2, 3, 6, and 12hours after resection. Signal intensities of the images were measured and their sequential changes were evaluated.Results: On T1WI, signal intensities of both tissue specimens fixed in formalin and ethanol and untreatedspecimens increased significantly during the first 30 minutes. The increased signal intensity then seen for 12hours was greater than on T2WI. On T2WI, signal ntensities of tissue specimens fixed in formalin and ethanol anduntreated specimens showed no significant changes within the first 30 minutes; after that, they showed less signalintensity change for 12 hours than on T1WI. Conclusion: To obtain MR images with the same signal intensities as invivo tissue, MRI of tissue specimens in the untreated state should be performed as soon as possible afterresection. On T2WI, signal intensities of tissue specimens were more similar to in vivo tissue than on T1WI.