PURPOSE: To compare spherical aberration, higher-order aberration, and contrast sensitivity of eyes implanted with aspheric (AcrySof IQ) or spherical (AcrySof Natural) intraocular lenses. METHOD: Seventy-five eyes implanted with posterior chamber intraocular lenses were divided into two groups: AcrySof IQ (35 eyes) and AcrySof Natural (40 eyes). Wavefront analysis (spherical, higher-order and total aberration) using iTace, and contrast sensitivity (under photopic and mesopic condition) using Optec 6500 were performed at 1 month and 3 months postoperatively. RESULT: One month after surgery, the IQ IOL (intraocular lens) group had lower values of spherical aberration (p<0.001) and higher-order aberration (p=0.048) than the Natural IOL group. The IQ IOL group also showed better contrast sensitivities at 1.5- and 3-cpd spatial frequencies in mesopic conditions. Three months after surgery, the IQ IOL group had less spherical aberration (p<0.001) and higher-order aberration (p=0.027) than the Natural IOL group and showed better contrast sensitivities at the 3-cpd spatial frequency in mesopic conditions. CONCLUSIONS: Aspheric AcrySof IQ IOL induced significantly less higher-order aberration and spherical aberration than AcrySof Natural IOL. The contrast sensitivity was better under mesopic conditions in the AcrySof IQ IOL-implanted group