Purpose: We intended to study effects of wearing the progressive lenses on legibility of Korean letters under the VDT circumstance. Methods: Fifty subjects wearing the progressive lenses and the single focus lenses were asked to find designated characters on web-pages under the VDT circumstance. We measured times for subjects to read the web-pages and numbers of missed characters, considering them as standards of legibility, and compare results of the progressive lenses with those of the single focus lenses by variables of the size and legibility of letters and the width of web-pages. Results: In case of the progressive lenses, all the times to read the web-pages and some of the numbers of missed characters increased with statistical significance. Smaller the character size, lower the legibility of character itself, and wider the width of web-page, the legibility tended to be seriously lowered by the progressive lenses. Conclusions: It is presumed that the intermediate part of progressive lenses with narrow visual field lowers the legibility of Korean letters under the VDT circumstance.