Abstract: Background and Objective: The house fly, Musca domestica L., has the ability to develop resistance against pyrethroid insecticides in a short exposure time. This study aimed to screen the susceptibility of house fly to lambda-cyhalothrin and determine the activities of metabolic enzymes in insect. Materials and Methods: House fly populations collected from different locations in Sharkia Governorate, Egypt were used. Bioassay experiments were carried out on 3rd larval instars of each population. Activities of metabolic enzymes were determined. Results: Data of bioassay experiments indicated that population collected from Kafr Sakr is 10.6-fold resistant to lambda-cyhalothrin. Other populations collected from San El-Hagar, Abo Kabir, Abo Hammad and Zagazig showed 8, 9.8, 6.9 and 7.5 fold of resistance as compared on LC50 levels. Biochemical assays revealed that San El-Hagar and Kafr Sakr populations have the highest significant activity of esterase, while Zagazig population showed the highest activity in carboxylesterase recording 2.58 fold higher than laboratory strain followed by populations from Kafr Sakr and San El-Hagar. Results of mixed function oxidase were significantly higher in both Zagazig and Abo Hammad populations with 1.3 and 1.3 fold than what recorded in the laboratory strain. Kafr Sakr and Abo Hammad populations showed the highest significant GST activity recording 174.7 and 170 mmol min–1 g–1 b.wt., respectively. Conclusion: The obtained results showed that populations collected from different locations in Sharkia Governorate have low to moderate resistance to lambda-cyhalothrin with the possible role of carboxylesterase. The existing resistance is a warning to carefully use lambda-cyhalothrin in control programs of this pest in the specified locations.