Fenvalerate, a commercially available pyrethroid insecticide, was tested for embryo toxic effects in chick. Different aqueous concentrations of fenvalerate, (0.1 and 0.05 ?g/ml) were injected in albumin of eggs on seventh day of incubation. Recoveries were made at 14th and 20th day of incubation. At 14 and 20 days, morphological studies revealed concentration dependent adverse effects of the insecticide. The developmental effects were loss in weight, reduction in crown rump length and short beak while eyes development showed no observable effects. The present study indicates that fenvalerate, is potentially dangerous to avian development even at very low dose concentrations. It is quite apparent that this insecticide must be used with utmost care and according to well think out plan. Fertilizers e.g. fenvalerate are the important factor for improving soil fertility and crop production. Insects/pests cause serious damage to crops. A common practice to use insecticide/pesticides for the inhibition of these insect/pest populations while maintain the agro-ecosystem. These chemicals are quite dangerous to human health and also cause destruction of non-target species most importantly poultry species present in the ecosystem. The toxic effects of these insecticide e.g. fenvalerate sometimes cause the lethality and mostly cause the developmental disorder thereby presenting economic loss to the farmers. The well-defined concentration of fenvalerate insecticide and their use for the soil productivity is of great importance as it can affect the other species present in that ecosystem and in rural areas the domestic chicken. The economic loss is also associated with it since the abnormal growth of chicken can lead to lethality causing the loss to the chicken breeders and farmers. The highly toxic effects of fenvalerate on the non-targets organisms provides base for the more investigation on the effects of fenvalerate on other different non-target organisms such as fish and avian species. The statistical hypothesis of the present study was found significantly associated with respect to the parameters of morphological abnormalities in chicken (loss in weight, reduction in crown rump length and short beak).