Deltamethrin (DLM) is a well-known pyrethroid insecticide which is widely used in the agriculture and home pest control due to restriction on the sale of organophosphate. DLM induced apoptosis is well known but its mechanism is still unclear. This study has been designed to find out its mechanism of apoptosis with the help of computational methods along with in vivo methods. The QikProp and ProTox results have shown that DLM has good oral absorption. The docking results reveal that DLM has a strong binding affinity toward the CD4, CD8, CD28 and CD45 receptors. Further, to understand the toxicity of DLM on lymphoid cells, a single dose of DLM (5 mg/kg, oral for seven days) has been administered to male Balb/c mice and cytotoxicity (MTT assay), oxidative stress indicators (glutathione, reactive oxygen species) and apoptotic markers (caspase-3 activity, DNA fragmentation) have been assessed in thymic and splenic single cell suspensions. Lowering of body weight, cellularity and loss in cell viability have been observed in DLM treated mice. The significant increase in ROS and GSH depletion in spleen and thymus, indicate the possible involvement of oxidative stress. The spleen cells appear more susceptible to the adverse effects of DLM than thymus cells. Further, for the amelioration of its effect, two structurally different bioactive herbal extracts, piperine and curcumin have been evaluated and have shown the cytoprotective effect by inhibiting the apoptogenic signaling pathways induced by DLM.