During the course of research in embryology on different species of birds; A case of monster chick embryo (Fayomy breed) of 19 days age of incubation was observed. The monster appeared as incomplete twins as some parts of the body are duplicated (limbs, wings, neck, urogenital system). This case may be derived from double ova ovulated at one time or any unknown mechanical factors. Other cases of monsters were recorded in eggs obtained from hens exposed to high tempreature and light for certain time . these cases were represented by Two normally well develop < /strong>ed newly hatched chickens connected together through the yolk stalk, other monster was represented by unhatched chick. It had an abnormal tibio-tarsal and tarso-metatarsal bones with sup < /strong>er number of digits in each limbs.