Global decline in frog populations is thought to indicate environmental damage caused by human
activity. Pollution especially chemicals are found to contaminate aquatic ecosystems and their animals
including fish and amphibians during their adult life and sensitive stages of development. Nonylphenol
ethoxylate (NPE) is one of the most dangerous chemicals that are recorded in aquatic environments,
bacterial degradation of nonylphenol ethoxylates produces more toxic nonylphenol (NP) which is
estrogenic both on vitro and vivo assays. In present work, the exposure of embryos of Egyptian toad
Bufo regularis to different sublethal doses of 4-nonylphenol (1.5, 2.5, and 3.5 μgl-1) resulted in mortality
rate increase and as a result some morphological malformations with histopathological changes in
some organs were revealed. This study indicated the destructive effects of 4-Nonylphenol on the
tadpoles of Egyptian toad.