We present an improved measurement of b-meson lifetimes using fully reconstructed B-decays produced in pp¯ collisions at s√=1.8 TeV, using 114 pb-1 of data collected at the Collider Detector at Fermilab. We obtain τ(B+)=1.636±0.058(stat)±0.025(syst) ps, τ(B0)=1.497±0.073(stat)±0.032(syst) ps and for the lifetime ratio τ(B+)/τ(B0)=1.093±0.066(stat)±0.028(syst).