Implementation of Good Agricultural Practices, establishing MRL for each combination agricultural crop/pesticide and determination of PHI, is an extensive process involving a lot of interested parties, such as agriculture scientists, analytical chemists, farmers, representatives of legislative and executive bodies, etc. All countries should be responsible for implementation of this process in order to prevent agricultural products with pesticides residues content higher than established MRL enter in food chain guaranteeing that safety standards are met and GAP have been applied in using pesticide formulations in agricultural crops. This paper describes the determination of dissipation rate of λ-Cyhalothrin, the active ingredient of insecticide Karate 2.5EC, used in grapes. The field samples have been submitted to analytical procedure in order to determine PHI. Normal and double dose have been used and one treatment for each dose has been applied followed by sampling successive days after the application. The AOAC analytical method was used to determine first the recovery coefficients of λ-Cyhalothrin in grapes in three different concentration levels. Later, the samples of grapes sprayed with Karate 2.5EC have been submitted to analytical procedure of sample processing, extraction, selective partition and quantitative determination using a GC-μ/ECD. The results obtained were compared to the Maximum Residues Limit (MRL) for λ-Cyhalothrin in grapes and PHI was determined.