OBJECTIVE To assess the efficacy and safety of implanting a bifocal diffractive intraocular lens (IOL) using the piggyback technique to provide pseudoaccommodation. METHODS Instituto Oftalmológico Fernández-Vega, Oviedo, Spain. METHODS This prospective noncomparative case series included 6 pseudophakic emmetropic patients who had a monofocal IOL implanted in the capsular bag. All eyes had secondary piggyback Acri. Twin bifocal diffractive IOL (Acri.Tec) implantation in the ciliary sulcus to provide pseudoaccommodation. Contralateral implantation of 1 Acri. Twin near-weighted 733D IOL in the nondominant eye and 1 Acri. Twin distance-weighted 737D IOL in the dominant eye was performed. Monocular and binocular best distance-corrected visual acuity and distance-corrected near visual acuity were evaluated 6 months after surgery. RESULTS The mean binocular best distance-corrected visual acuity and distance-corrected near visual acuity were -0.080 +/- 0.056 logMAR and -0.016 +/- 0.037 logMAR, respectively. There were no statistically significant differences in binocular best distance-corrected acuity after the piggyback IOL implantation (P>.01). The differences between monocular and binocular visual acuity were the result of the distance- and near-weighted light distribution of the Acri. Twin IOLs. All IOLs were well centered with no tilt. Two eyes had pupillary capture of the optic. CONCLUSIONS The Acri. Twin bifocal diffractive IOL implanted in the ciliary sulcus using the piggyback technique provided pseudoaccommodation in emmetropic pseudophakic eyes. Binocular implantation of these IOLs should be performed considering the differences in light distribution of the distance-weighted IOL and the near-weighted IOL models.