Background: Magnetization transfer saturation (MTsat) imaging was developed to reduce T1 dependence and improve specificity to myelin compared to the widely used MT ratio (MTR), while maintaining a feasible scan time. Knowledge of MTsat reproducibility is necessary to apply MTsat in preclinical neuroimaging. Purpose: To assess the test-retest reproducibility of MTR and MTsat in the mouse brain at 9.4 T and calculate sample sizes required to detect various effect sizes. Study Type: Prospective. Animal Model: C57Bl/6 Mouse Model (6 females and 6 males, aged 12 to 14 weeks). Field Strength/Sequence: Magnetization Transfer Imaging at 9.4 T. Assessment: All mice were scanned at two timepoints (5 days apart). MTR and MTsat maps were analyzed using mean region of interest (ROI), and whole brain voxel-wise analysis. Statistical Tests: Bland Altman plots assessed biases between test and retest measurements. Test retest reproducibility was evaluated via between and within-subject coefficients of variation (CV). Sample sizes required were calculated (at a 95 % significance level and power of 80 %), given various minimum detectable effect sizes, using both between and within-subject approaches. Results: Bland Altman plots showed negligible biases between test and retest sessions. ROI based and voxel-wise CVs revealed high reproducibility for both MTR (ROI: CVs < 8 %) and MTsat (ROI: CVs < 10 %). With a sample size of 6, changes on the order of 15% can be detected in MTR and MTsat, both between and within subjects, while smaller changes (6 to 8 %) require sample sizes of 10 to 15 for MTR, and 15 to 20 for MTsat. Data Conclusion: MTsat exhibits comparable reproducibility to MTR, while providing sensitivity to myelin with less T1 dependence than MTR. Our findings suggest both MTR and MTsat can detect moderate changes, common in pathologies, with feasible preclinical sample sizes. Keywords: magnetization transfer ratio, magnetization transfer saturation, reproducibility, preclinical rodent imaging