PURPOSE To determine the appropriate correction of predicted intraocular lens (IOL) power for sulcus fixation and to prospectively assess the validity of the obtained correction value in patients having sulcus fixation. SETTING Department of Ophthalmology, Saiseikai Kurihashi Hospital, Saitama, Japan. METHODS The postoperative refraction, virtual in-the-bag IOL power for the same postoperative refraction, predicted refraction with an increase in in-the-bag IOL power by 0.50 to 2.00 diopters (D), and effective lens position (ELP) in 30 eyes with a normal axial length after sulcus fixation were retrospectively evaluated. The results were confirmed prospectively in 16 other eyes requiring sulcus fixation. RESULTS A significant myopic shift (mean 0.78 D +/- 0.47 [SD]) from the predicted refraction occurred after sulcus fixation (P<.0001). The mean virtual IOL power was 1.11 +/- 0.67 D higher than that of the actual sulcus-fixated IOL. The difference between the predicted refraction and the refraction after sulcus fixation was less when the difference in IOL power was 1.00 D. The ELP of the IOLs was 0.75 mm shorter using A-mode measurement and 0.62 mm shorter using back calculation from the theoretical formula with sulcus fixation than with in-the-bag fixation. In the prospective study, there was a small refractive error (mean -0.06 +/- 0.19 D) when the planned IOL power was reduced by 1.00 D for sulcus fixation. CONCLUSION For sulcus fixation in eyes with a normal axial length, the IOL power should be 1.00 D less than the power for in-the-bag fixation.