A backlight assembly includes a light source unit a light guiding plate and an optical changing pattern. The tight source unit includes a light source, a first lens portion enclosing the light source and a second lens portion positioned on the first lens portion. The second lens portion has a concave shape at an upper face. The light guiding plate includes an upper face and a lower face. The light guiding plate has a groove formed on the lower face to enclose at least a portion of the light source unit. The light guiding plate guides the light generated from the light source unit. The optical path changing pattern is formed on the upper face of the light guiding plate, and faces the light source unit. As a result, an optical distribution of the backlight assembly may be uniformized, and a size of the backlight assembly may be reduced.