We studied the kinematic rupture process of the moderate magnitude (Mw 5.9), 1999 Athens earthquake using broadband seismic recordings at regional distances. The Apparent Source Time Functions (ASTF), obtained by retrieving the wave propagation and site effects from the seismic recordings using an empirical Green's function method, indicate a rather complex rupture with a source directivity primarily pointing towards Athens. To further characterize the faulting, we inverted the ASTFs for the kinematic history of the rupture using a damped-least square inversion scheme with inequality constraints. The rupture extent is delimited by a 10 km along-strike ¿20 km along-dip zone. The mean slip amplitude on the observed rupture area is equal to 25 cm. The slip concentrates in two elongated zones with amplitudes reaching locally 60 cm. The total rupture lasted between 5 and 6 s.