Background There is limited data in the literature regarding the role of nonarthrographic MRI for detecting biceps pulley (BP) lesions. Purpose To assess the accuracy of nonarthrographic MRI for detecting BP lesions, and to evaluate the diagnostic value of various MRI signs (superior glenohumeral ligament discontinuity/nonvisibility, long head of biceps (LHB) displacement sign or subluxation/dislocation, LHB tendinopathy, and supraspinatus and subscapularis tendon lesions) in detecting such lesions. Study Type Retrospective. Population 84 patients (32 in BP-lesion group and 52 in BP-intact group-as confirmed by arthroscopy). Field Strength/Sequence 1.5-T, T1-weighted turbo spin echo (TSE), T2-weighted TSE, and proton density-weighted TSE spectral attenuated inversion recovery (SPAIR) sequences. Assessment Three radiologists independently reviewed all MRI data for the presence of BP lesions and various MRI signs. The MRI signs and final MRI diagnoses were tested for accuracy regarding detecting BP lesions using arthroscopy results as the reference standard. Furthermore, the inter-reader agreement (IRA) between radiologists was determined. Statistical Tests Student's t-tests, Chi-squared, and Fisher's exact tests, and 4-fold table test were used. The IRA was calculated using Kappa statistics. A P-value <0.05 was considered statistically significant. Results The sensitivity, specificity, and accuracy of nonarthrographic MRI for detecting BP lesions were 65.6%–78.1%, 90.4%–92.3%, and 81%–86.9%, respectively. The highest accuracy was noticed for the LHB displacement sign (84.5%–86.9%), and the highest sensitivity was registered for the LHB tendinopathy sign (87.5%). Furthermore, the highest specificity was observed for the LHB displacement sign and LHB subluxation/dislocation sign (98.1%–100%). The IRA regarding final MRI diagnosis and MRI signs of BP lesions was good to very good (κ = 0.76–0.98). Data Conclusion Nonarthrographic shoulder MRI may show good diagnostic accuracy for detecting BP lesions. The LHB displacement sign could serve as the most accurate and specific sign for diagnosis of BP lesions. Level of Evidence 3 Technical Efficacy Stage 2