The rupture process of the 1999 Turkey earthquake is examined using both near-field strong motion data and teleseismic body wave data. The derived source parameters are as follows: (strike, dip, slip)=(268¿,86¿,180¿), nearly pure strike-slip; the seismic moment, Mo=1.7¿1020 Nm (Mw=7.4); the source duration=20 sec; the fault length=70 km; the fault width=15 km. The rupture process is characterized by an asymmetric bilateral rupture propagation and smooth slip. It consists of two major fault segments, a rupture propagating to the west and a second rupture propagating to the east. The maximum dislocation and the maximum dislocation velocity are 6.3 m and 2.7 m/s, respectively, both found at the former segment. The average dislocation is about 4 m. The extent of the coseismic rupture suggests that a considerable part of the anticipated seismic gap remains unruptured. ¿ 2000 American Geophysical Union