The present work is concerned with the determination of pesticide residues in serum samples of Karachi people. In the present study enzyme levels and blood parameters were checked in the blood samples from collected Karachi population to assay the pesticide residues in their blood and also observed the morphological chemical changes. Effects of residues were observed on the enzyme level and blood parameters in the donors. Regarding enzyme levels, GOT, ALP and Cholinesterase had higher levels in almost all the donors. Organochlorine level was found to be high in those persons who were employees in government chemical department as compared to others private department. The variation was also noted among their ages. Both young and old age people were found to contain considerable quantities of organochlorine pollutants. Regarding blood parameters all donors had significant variation (i.e., increase or decrease level) possibly due to cumulative effect of residues. In 40% of the samples Hb, Hct, RBC, neutrophils and eosinophils had decreased level which may be due to toxic effects of pesticides.