The lifetime of the Lambda(b)(0) baryon has been measured using 3.6 mi
llion hadronic Z(0) decays recorded by the OPAL detector at LEP from 1
990 to 1994. A sample of Lambda(b)(0) decays is obtained using partial
ly reconstructed semileptonic decays involving Lambda(c)(+)l(-) combin
ations, where the Lambda(c)(+) is reconstructed from its decay to a pK
(-) pi(+) final state. From the 69 +/- 13 Lambda(c)(+)l(-) combination
s attributed to Lambda(b)(0) decays in this data sample, we measure ta
u(Lambda(b)(0)) = 1.14(-0.19)(+0.22) +/- 0.07 ps, where the errors are
statistical and systematic, respectively.