The eye-writing method predefines a symbol set containing symbols with distinct writing traces. A user of this method rotates his or her eye balls to "write" a symbol according to its designated writing trace. Meanwhile, the eye movement is detected using a suitable technique such as the electro-oculography, which measures voltage differences on the skin around the user's eyes. Distinct features of the acquired eye-movement signals are extracted in order to determine which symbol, among those in the symbol set, the user's eyes have just written. An eye-writing system has been implemented in this study. Tests on subjects with no known disabilities have been conducted and the performance has been evaluated. The study found that eye-writing system is potentially useful for facilitating communication of sever ALS patients who have lost most of their oral speaking and handwriting abilities.