We present a measurement of the branching ratio BR(KS --> pi e nu) performed
using the KLOE detector. KS mesons are produced in the reaction e+ e- --> phi
--> KS KL at the DAFNE collider. In a sample of about 5 million KS-tagged
events we find 624 +- 30 semileptonic KS decays. Normalizing to the KS --> pi+
pi- count in the same data sample, we obtain BR(KS --> pi e nu) = (6.91 +-
0.37) 10^-4, in agreement with the Standard Model expectation.Comment: 9 pages, 5 Encapsulated Postscript figures. Submitted to Phys. Lett.