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One of the most common compounds in pesticide formulations, plastics, and papers is 4-nonylphenol (4-NP). It is contained in agricultural, industrial, and wastewater effluents, which when discharged into surface waters affect aquatic fauna. Therefore, the present study aimed to use Biomphalaria alexandrina snails to evaluate the chronic toxicity of 4-NP. Its concentrations in collected water samples from Giza Governorate ranged from 400 to 1600g/l. Based on these environmentally relevant concentrations, laboratory experiments were carried out using standard 4-NP to investigate the effect of three concentrations; namely 400, 750, and 1600g/l. Survival rate of the exposed snails to 4-NP concentrations was affected after 4weeks. Reproduction of the exposed snails to 4-NP concentrations was lower than that of the control at 30 degrees C, while the exposed snails to 400g/l of 4-NP showed maximum reproduction at 15 degrees C. The lowest hatchability percentage was recorded with egg masses laid by the exposed snails to 400 and 1600g/l of 4-NP at 15 and 30 degrees C, respectively. Furthermore, the results showed fluctuated levels of progesterone, estradiol, and testosterone depending upon the concentration and the temperature, which played a key role in determining the degree of 4-NP toxicity.