About 35% of intraocular lenses now implanted in the United States are narrow profile lenses, measuring on the average 5.0 mm by 6.0 mm. This study sought to determine whether these lenses cause unwanted optical images with a decrease in the quality of vision. Seventy-five eyes with a 5.0 mm x 6.0 mm intraocular lens (IOL) were compared with 75 eyes with a 6.5 mm IOL. All patients had capsulorhexis, phacoemulsification, and capsular fixation of the IOL. There was no statistically significant difference in unwanted visual images (16% and 20%, respectively), ability to drive at night (79% and 69%), or patient satisfaction. Careful patient selection is, however, important.