The Beijing Spectrometer (BES) Collaboration has observed exclusive pa
ir production of D-s mesons at the Beijing Electron-Positron Collider
(BEPC) at a center-of-mass energy of 4.03 GeV. The D-s mesons are dete
cted in the phi pi(+), (K) over barK-0(+), and (K) over bar(0)K(+) de
cay modes; two fully reconstructed events yield the value (3.9 (-1.9 -
1.1) (+5.1 +1.8))% for the D-s branching fraction to phi pi. This is t
he first direct, model-independent measurement of this quantity.