A survey was conducted on 1,474 adult sheep from 73 flocks distributed in the 13 provinces of Syria. Faecal egg and larval nematode outputs were studied. Marshallagia and Nematodirus infections were higher in the driest areas; infections by other nematodes, Dictyocaulus and small lungworms (Cystocaulus and Muellerius) were higher in the more rainy areas. A long transhumance limited small lungworm infections, which were higher in flocks using wet night shelters.