In our work we study the toxic effects of the prepared pyridine and pyradazine derivatives. Five compounds have been synthesized in pure state as reported procedures, and their toxicity as potential insecticidal agents against adult and nymphs of Aphis nerii were screened. The toxicity data in adults, exhibited that compound 6a is more toxic than other synthesized compounds, which LC50 was1.04 ppm while, in nymph compound 4a is more toxic than other synthesized compounds, which LC₅₀ was 0.02 ppm. The other screened compounds showed weak to strong toxicological activity. The structure-activity relationships (SAR) for these compounds were also discussed.