This study determined the in-ovo antiviral effect of crude Methanolic leaf extract of Cymbopogon citratus on Newcastle disease virus. Cold extraction was carried out using analytical grade methanol. Phytochemical screening of the crude extract was carried out using standard procedures. Antiviral assay was carried out in nine-day old specific pathogen free embryonated hens’ eggs in three designs made of five eggs per group (Virus with extract, virus only and un-inoculated groups) with concentrations ranging from 12.5 to 100 mg ml−1. Egg toxicity of the extract was determined for concentrations of 12.5, 25, 50, 100, 200, 300 and 400 mg ml−1. Inoculated eggs were incubated at 37 °C and observed daily for 96 h for embryo survival and mortality. Spot haemagglutination was carried out on bacteria-free allantoic fluid from the embryonated eggs to detect the presence of the virus. Phytochemical assay revealed the presence of saponins, flavonoids, steroids, terpenes, phlebotannins and terpenoids. Mild toxicity was observed at concentrations of 100 mg ml−1 and above. There was no haemagglutination of fluid from the eggs inoculated with a combination of Virus and extract at concentrations of 50 and 100 mg ml−1. The current findings demonstrated that leaf extract of Cymbopogon citratus has potential medicinal value as well as antiviral activity against Newcastle disease virus in-vivo. The specific mechanism of action remains to be studied to further elucidate on its potential as a therapeutic product for the treatment of Newcastle Disease.