The rapidly increasing use of cell phones since late 1990s has caused a general concern on the possible hazardous health effects of exposure to radio frequency electro-magnetic radiation (EMR) emitted by them. While considering the bio-logical effects of EMR on the human body, its intensity, frequency of radiation and duration of exposure are important determinants. Many researchers have reported several harmful effects associated with exposure to radio frequency EMR while some of the studies could not show any effect at all. The present study addresses the effect of cell phone emanating EMR in 900 MHz radio fre-quency (widely used) range in determining the health of developing chick em-bryos. A standard cell phone hand set working at a radio frequency band of 900 MHz, power of 2 W and Specific Absorption Ratio (SAR) 0.37W/Kg was used. Sets of fertile hen eggs (Gallus domesticus) in batches were incubated in a spe-cially designed incubator (radio transparent) at a constant temperature, humidity. During incubation one set of eggs was exposed for a short period and the other set was exposed for a longer duration to radiation of the cell phone while the remaining set of eggs was not exposed to any radiation. It was observed that exposure to radiation increased the mortality in chick embryos. It was further observed that the rate of mortality is the function of EMR energy comprising power density at the egg location and duration of exposure.