A study on the occurrence and seasonal incidence of hydatid cysts of sheep, goats and cattle was carried out during 2008 and 2009 by weekly regular visits to Mosul abattoir and other areas i.e. outside abattoir. All slaughtered livestock were of local breed, of both sexes, originated from various areas of Mosul and were of different ages having non descriptive features. Visual inspection and palpation of the lesions were followed in this study. Of 4800 sheep, 960 goats and 720 cattle were examined, 96 sheep, five goats and four cattle were found to harbour the cysts representing infection rate of 2%, 0.52% and 0.55%, respectively. The lowest seasonal incidence was observed in winter for sheep (3.16%) and goats (1.25%). The lowest level of incidence was 0.16% for sheep and 0% for goats was noticed in summer. However, in cattle no infection was taken place in winter and autumn but 1.11% infection rate was equally seen in summer and spring. The preponderant site of cyst was the liver in sheep (46.8%) and goats (40%). In cattle the commonest location of the cyst was the lung (50%) followed by mixed site of liver and lung (25%) and liver (25%). The results indicated that only fertile cysts were present in the sheep representing 83.33% of fertility percentage. The number of cysts in the infected organs ranged between 1-16, 1-6 and 1- 10 for sheep, goats and cattle, respectively. It can be concluded that only sheep play a major role in dissemination of hydatidosis. However, being anthrozoonotic, potential risk may be increased due to incorrect disposal of infected offal with unhygienic slaughter protocols.