OBJECTIVE Inferior oblique recession (Fink's technique) is one of various surgical procedures to manage congenital superior oblique muscle palsy. The authors aimed to determine the effectiveness of this operation in reducing vertical deviation and torsional deviation, and to assess the dose-effect relationship. METHODS Fifty-eight patients presenting with unilateral congenital superior oblique palsy had an inferior oblique recession of 6 mm, 8 mm, or 10 mm (16, 35, and 7 patients, respectively). Vertical deviation and torsional deviation were measured before and after surgery by means of the dark red glass dissociation in front of Harms'tangent screen and the data were analyzed retrospectively. RESULTS A cure rate of 88% was achieved, with no complications, and no overcorrections. For the 34 patients for whom long-term follow-up was possible (mean 2.8 years), final median postoperative vertical deviations and torsional deviations were 0.5 degrees and 0 degrees, respectively, both in primary position and in adduction upgaze. CONCLUSIONS Inferior oblique weakening by recession proves to be an efficient and safe procedure for congenital superior oblique palsy, and its effect on vertical deviation can be predicted on the extent of recession. The operation can therefore be adapted to the patient, depending on the degree of the preoperative deviation.