Purpose: To evaluate the surgical and functional results of full horizontal te ndon rectus muscle transposition to the superior rectus (SR) insertion, augmente d by posterior fixation sutures, in patients with double-elevator palsy (DEP). Design: Retrospective nonconcurrent interventional comparative case series. Part icipants: Fourteen consecutive patients with DEP. Intervention: Six patients tre ated for DEP by vertical transposition of the horizontal muscles to the SR inser tion (Knapp procedure)-were compared with 8 patients treated by the Knapp proce dure combined with fixation of the transposed muscles to the sclera, adjacent to the SR, with nonabsorbable sutures. Main Outcome Measures: Postoperative ocular alignment, ductions, binocular functions, and rate of reoperation. Results: Ocu lar deviation: Mean distance and near deviations decreased by 84%and 83%, resp ectively (P=0.012), in the augmented-surgery group versus 48%and 47%, respect ively (P = 0.03), in the standard-surgery group. Duction: Mean elevation defici ency in abduction and adduction improved by 64%and 65%, respectively (P=0.01), in the augmented surgery group versus 42%and 55%(P = 0.02) in the standard gr oup. Binocular functions: 3 patients (37%), all in the study group, gained bino cular function. Reoperation was required in 5 patients (83.3%) in the control g roup. The difference in postoperative improvement between the groups was statist ically significant for all 4 parameters. No postoperative complications or ducti on anomalies were observed during the follow-up period of 15.4 months (standard deviation, 5.5). Conclusions: The augmented Knapp procedure with superior poste rior fixation suture is the preferred surgical treatment for patients with DEP. Its use in this series avoided the need for multiple surgeries on other extraocu lar muscles. Purpose: To evaluate the surgical and functional results of full horizontal tendon rectus muscle transposition to the superior rectus (SR) insertion, augmente d by posterior fixation sutures, in patients with double-elevator palsy (DEP). Design: Retrospective nonconcurrent interventional comparative case series. Part icipants: Fourteen consecutive patients with DEP. Intervention: Six patients treted for DEP by vertical transposition of the horizontal muscles to the SR (tion procedure) -were compared with 8 patients treated by the Knapp proce dure combined with fixation of the transposed muscles to the sclera, adjacent to the SR, with nonabsorbable sutures. Main Outcome Measures: Postoperative ocular alignment, ductions, binocular functions, and rate of reoperation. Results: Ocu lar deviation: Mean distance and near deviations decreased by 84 % and 83%, respctively (P = 0.012), in the augmented-surgery group versus 48% and 47%, respectively (P = 0.03), in the standard-surger y group. Duction: Mean elevation defici ency in abduction and adduction improved by 64% and 65%, respectively (P = 0.01), in the augmented surgery group versus 42% and 55% (P = 0.02) in the standard group. The difference in postoperative improvement between the groups was statistically significant for (3) (3) patients (37%), all in the study group, gained bino cular function. all 4 parameters. No postoperative complications or ducti on anomalies were observed during the follow-up period of 15.4 months (standard deviation, 5.5). Conclusions: The augmented Knapp procedure with superior poste rior fixation suture is the preferred surgical treatment for patients with DEP Its use in this series avoided the need for multiple surgeries on other extraocu lar muscles.