Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), tomato leaf miner, is one of the most devastating insect pests that attack tomato crops. T. absoluta larvae destroy tomato plants by producing large galleries in tomato leaves and burrowing stalks, apical buds, green and ripe fruits. This larva causes a major economic effect on tomato industry. Insecticides are commonly used to control this pest in tomato fields. The aim of this study is to determine the susceptibility levels of T. absoluta populations and biochemical analysis of mechanism(s) involved in chlorantraniliprole and metaflumizone metabolism, registered in Turkey for use against T. absoluta. IRAC bioassay method was used to determine the resistance ratios of these insecticides. Resistance ratios ranged between 7.2-and 1.7-folds for chlorantraniliprole, and 4.0- and 1.8-folds for metaflumizone in T. absoluta field populations. NADPH-Cytochrome P450 reductase, glutathione S-transferase, and esterase activities were determined by conducting biochemical assays in field populations of T. absoluta. While NADPH Cytochrome P450 reductase activity showed an increase only in Antalya population (1.9-fold), glutathione S-transferase activity showed an increase only in Adana population (1.2-fold). However, esterase activities were increased both in Adana (1.3-fold) and Ankara (2.2-fold) populations of T. absoluta.