Purpose: To assess the predictability of the algorithm used to determine the amount of tissue resection for conjunctival-Müellerectomy during blepharoptosis repair. Methods: A consecutive case series of all patients undergoing conjunctival-Müellerectomy during blepharoptosis repair between July 2001 and February 2005. All of the cases had a positive phenylephrine test, and the mean preoperative upper marginal reflex distance (MRD₁) was +1.60 mm (range: −1 ±3.5 mm). Each patient underwent excision according to the following algorithm: 10 mm of resection for 2 mm of ptosis, 8 mm of resection for 1.5 mm of ptosis, and 6 mm of resection for 1 mm of ptosis. Results: Fifty-five patients underwent conjunctival-Müellerectomy during blepharoptosis repair on 73 eyelids, using the above algorithm. Thirty-seven cases were unilateral and 18 were bilateral. The mean postoperative MRD₁ was +3.42 mm (range 0–+4.5 mm). Postoperative symmetry was found in 42 of 55 patients (76.4%) after one surgical procedure. Patient satisfaction based on contour, symmetry and height after one repair was achieved in 52 of 55 patients (94.55%). There were three reoperations for previous undercorrection. Conclusion: This algorithm quantifies conjunctival-Müellerectomy during blepharoptosis repair. Excellent and very predictable results are obtained by a technique that is both simple and achievable in a short operating time.