Pesticides are widely used chemicals making human exposure to pesticides a realistic possibility. Biomonitoring is a common and useful tool for assessing human exposure to pesticides. Pyrethroids are effective insecticides that are often used in household sprays, aerosol bombs, insect repellents, pet shampoos, and lice treatments. Using products containing these compounds will expose people to these chemicals. Since these compounds frequently are used on crOPs, they are often detected in fruits and vegetables. Biomonitoring of exposure is a useful tool for assessing exposure to pesticides. Biomonitoring involves the measurement of the parent pesticide, its metabolite or reaction product in biological media, typically blood or urine, to determine if an exposure has occurred and the extent of that exposure. Although not without its limitations, biomonitoring has great utility in integrating all routes of exposure allowing for one exposure measurement. Pesticides have much shorter environmental half-lives and tend not to bioaccumulate. In fact, from humans within 24 hr as the parent pesticide, a mercapturic acid detoxification product, oxidative or dealkylation metabolites, and/or glucuronide or sulphate-bound metabolites. However, because of the heavy agricultural and residential use of these chemicals, humans are continually exposed to many of these chemicals. The objective of the present study was to explore modification in toxico-pathological responses of rats treated with lambda-cyhalothrin (commercially called karate). Rats (250 g weight), were gavaged by 1/100 LD50 for 4 weeks (one dose every week). Blood was collected before dosing and after 48 hours from the treatment. Enzyme activities were assayed in the plasma samples obtained. Glutamate oxaloacetate transaminase (GOT), Glutamate pyruvate transaminase (GPT), Alkaline phosphatase (ALPH) and Glucose. The results showed a decrease in RBC; WBC and Hb. This probably explained by the effect of lambda cyhalothrin on the erythropoiesis and the destruction of cells. An increase of plasma enzyme activities in GOT and GPT were recorded, explain a high energy-generating product. The histopathological results showed alteration on the target organs such as liver and kidney, these biochemical and histological modifications are probably due to the effect of lambda cyhalothrin or their metabolites.