Background Numerous operative techniques have been described for the treatment of massive rotator cuff tears with severe retraction where anatomical repair is impossible. Purpose To evaluate the outcome of massive rotator cuff tears repaired using the biceps interposition technique. Study Design Case series; Level of evidence, 4. Methods Between April 2000 and April 2004, 31 shoulders with irreparable massive rotator cuff tears and associated degenerative lesions of the biceps tendon were included for analysis. Open procedures were performed in 15 cases (open group), while 16 patients underwent arthroscopic procedures (arthroscopic group). The mean follow-up period was 32 months (range, 24-67 months). Results The overall University of California at Los Angeles score at the last follow-up was 31.1 points (range, 21-35). The clinical outcome was excellent in 15 (48.4%) and good in 13 (41.9%) cases. Three patients (9.7%) had poor outcome. There was 1 case of reoperation in the open group for a retear. The mean preoperative Constant score, which was 44.6 points (range, 8-70) in the open group and 51.8 points (range, 24-70) in the arthroscopic group, improved to 80.7 points (range, 37-88) in the former and 83.5 points (range, 57-96) in the latter. The University of California at Los Angeles score improved from preoperative means of 11.3 points (range, 6-16) and 13.6 points (range, 6-19) to 29.5 points (range, 9-33) and 32.6 points (range, 21-35), respectively. However, the differences between the scores in both the categories were not statistically significant (P = .412 and .198, respectively). According to the postoperative repair integrity analyzed with use of magnetic resonance imaging in 14 of 16 cases with arthroscopic augmentation, 9 (64.3%) presented complete healing. Conclusion The biceps tendon interposition technique for massive rotator cuff tears offers a possible improvement in the clinical outcomes and is comparable to that of conventional repair. As well, the augmentation technique using the tenotomized biceps as potential graft for rotator cuff tears is particularly useful in bridging the gap in immobile massive rotator cuff tears with posterior defects and retraction.