A projection lens system for enlarging and displaying on a screen an original image from an image generating source, includes a first lens having positive refractive power, a second aberration correction lens, and a third lens, positioned nearest the image generating source and having a concave lens surface thereof facing the screen. The third lens has a profile such that its refractive power at a marginal area adjacent a peripheral edge thereof is less than its refractive power at an area adjacent an optical axis of said projection lens system. The surface of the third lens facing the image generating source is in contact with a cooling liquid which cools the image generating source.