Natural light always plays important role in designing of residential apartments in terms of energy saving and health of lifestyle. To find a practical approach for saving electricity energy in lightening of dark places has always been a challenging topic in recent years. Most existing studies on the interior lightening by using sunlight in architectural concepts have focused on position of windows and patio in plans. This paper describes a new application of optical fibers for transferring sunlight into the rooms by conducting an experimental test. The experimental tests indicated that a group of optical fibers can successfully conduct the natural light from the roof of an apartment in to dark spots through walls. Also, from the outcomes it is concluded that the daytime running electricity lamps can decrease in compare with traditional methods.