We have measured the lifetime of the <(Sigma)over bar>(-) using the Fermila
b, Proton Center 375 GeV/c charged hyperon beam. We obtained (80.43+/-0.80/-0.14) ps. We also measured the lifetime of the Sigma(+), obtaining (80.38
+/-0.40+/-0.14) ps, in agreement with the Particle Data Group value. A dir
ect comparison between the two lifetimes from the ratio of the decay curves
gives a fractional lifetime difference of Delta tau/<(tau)over bar>=(-0.06
+/-1.12)%, consistent with equal lifetimes for baryon and antibaryon as req
uired by CPT invariance.