Quenching mechanisms and kinetics of $alpha$-, $eta$-, $gamma$-, and $delta$-tocopherol in photosensitized oxidation of lard were studied. Lard at 0.03, 0.07, 0.11, and 0.3 M in methylene chloride containing $4.4{ imes}10^{-6};M$ chlorophyll and 0, 0.1, 0.3, and 0.6 mM $alpha$-, $eta$-, $gamma$-, and $delta$-tocopherol were stored under light for 4 hr, respectively. Oxidation was determined by headspace oxygen and peroxide value. Tocopherols prevented the photosensitized oxidation of lard (p<0.05). Steady state kinetic study showed that $alpha$-, $eta$-, $gamma$-, and $delta$-tocopherol prevented the photosensitized oxidation of lard by quenching singlet oxygen. Singlet oxygen quenching rates of $alpha$-, $eta$-, $gamma$-, and $delta$-tocopherol by headspace oxygen depletion were 1.86, 2.39, 2.47, and $2.11{ imes}10^7/M/sec$, respectively. The quenching rates of $alpha$-, $eta$-, $gamma$-, and $delta$-tocopherol by peroxide value were 1.42, 1.11, 0.97, and $0.42{ imes}10^7/M/sec$, respectively. The quenching rates of tocopherols were slightly different depending on the measurements of oxidation.