  We present a measurement of the branching ratio of the CP violating decay
KL->pi+pi- performed by the KLOE experiment at the phi factory DAFNE. We use
328 pb-1 of data collected in 2001 and 2002, corresponding to ~ 150 million
tagged KL mesons. We find BR(KL->pi+pi-) = $(1.963 +/- 0.012 +/- 0.017)x 10^-3.
This branching ratio measurement is fully inclusive of final-state radiation.
Using the above result, we determine the modulus of the amplitude ratio
|\eta_{+-}| to be (2.219 +/- 0.013)x 10^{-3} and |\epsilon| to be (2.216 +/-
0.013)x 10^{-3}.
