ABSTRACT
In this study, the gastrointestinal nematodes of 75 sheep and their seasonal prevalence were investigated during March 2003-2004, in the Sanliurfa district, in Turkey. Fifty-seven (76 %) of the sheep under investigation were infected with gastro-intestinal nematodes. Eleven nematode species were detected. A total of 2,711 nematodes were collected from the digestive system of the infected sheep. The total number of parasites in each infected animal ranged from 1-977. The average number of parasites in each sheep was found to be 47.5. The number of nematode species in each animal also ranged from 1-5. Most of species in the infected sheep was found to be as follows; Ostertagia marshalli, O. occidentalis, O. circumcincta, N. spathiger, N. filicollis, T. ovis, and T. skrjabini.