To assess and compare the diagnostic performance of magnitude-reconstruction chemical-shift-encoded magnetic resonance imaging (MRI-M) and complex-reconstruction chemical-shift-encoded magnetic resonance imaging (MRI-C) for diagnosis of hepatic steatosis in subjects with severe obesity without known non-alcoholic fatty liver disease (NAFLD), using contemporaneous histology as reference. This is an IRB-approved, HIPAA-compliant, two-center, cross-sectional study of a larger prospective trail that recruited patients without known NAFLD consecutively between October 2010 and March 2015 to undergo research MRI exams 1-2 days prior to clinical-care weight-loss surgery. Proton denisty fat fraction (PDFF) was estimated using MRI-M and MRI-C. Liver biopsies were obtained intraoperatively. Using histologically-determined presence of steatosis as the reference standard, receiver operating characteristics (ROC) analyses were used to identify MRI-M- and MRI-C-derived PDFF thresholds for diagnosing steatosis. Bootstrapped-based tests were used to compare their diagnostic performace. A total of 81 patients (67 female, 14 maile, average age 48.2) were recruited for this study. MRI-M and MRI-C had areas under the ROC curve of 0.951 and 0.947, respectively, for diagnosing hepatic steatosis. for MRI-M, the Youden-index-based PDFF threshold of 6.5% provided 0.87 sensitivity (95% confidence internal: 0/75, 0.95), 0.96 specificity (0.81, 0.99), and 0.90 total accuracy (0.82, 0.96). For MRI-C, a PDFF threshold of 6.8%, provided a 0.90 sensitivity (0.77, 0.96), 0.96 specificity (0.81, 0.99), and 0.91 total accuracy (0.83, 0.97). Differences in performance parameters between MRI-M and MRI-C were not statistically significant. Conclusion: MRI-M- and MRI-C-derived PDFF is accurate for non-invasive diagnosis of hepatic steatosis in subjects with severe obesity.