This work characterized the developmental toxicity (including, maternal, embryo and fetotoxicity) of imidacloprid and cyanophos in pregnant female rats. The pregnant rats were daily orally administered 12.1, 24.2 and 48.4 mg / kg b. wt. / day of imidacloprid and 4, 6 and 8 mg cyanophos / kg b. wt. / day during organogenesis period. The present study showed that, the LD50 values of the tested insecticides were found to be 484.06 for imidacloprid and 807.60 mg / kg b. wt. for cyanophos. These results reflect that, cyanophos produced a significant decrease on maternal weight gain at the highest dose. For the organ weight ratios, cyanophos compound was more effective than the other compound. According to clinco-biochemical aspects such as, liver functions (e.g., ALT, AST, ALP, AchE, T.P and Alb) and kidney functions (e.g., Urea and Creatinine) and histopathological alternations, cyanophos was more toxic than imidacloprid and the two tested compounds showed severe histopathological lesions in brain and kidney more than in liver. According to the teratogenic study of the two insecticides, the external morphology of uterus and external morphology of feti parameters were affected. Skeletal malformations, wavy ribs, reduce or absence of sternbrae, and skull incomplete ossification were observed in feti of treated dams. The visceral examinations of available feti showed cleft palate, dilation of lateral ventricles and cerebral hemispheres, dilated renal pelvis, distended urinary bladder with urine, and hypertrophy in some fetal organs.