This study was carried out to determine lungworm species and their prevalence, evaluate the effect of host age and breed oil the infections and the correlation between faecal larvae counts and adult lung worms counts in sheep in Bursa Province, Turkey. A total of 104 sheep of different age and breed were examined for the lungworm infection. prevalence of infection was 45.1% and 62.5% by coproscopy and necropsy, respectively. The faecal examination and postmortem showed Dictyocaulus filaria (23%; 31.7%), Cystyocaulus ocreatus (24%; 31.7%) and Protostrongylus rufescens (3.8%; 5.8%). Seven (6.7%) and six (5.7%) sheep had mixed infections with two nematode species in necropsy and faecal examinations, respectively. There was a significant difference (p<0.05) between >4 year old and <4 year old age groups. There was no significant difference in the prevalence of lungworm infections in different sheep breeds. Although there was a positive correlation between larval excretion in faeces and lung nematode counts, reliable regression equations could not be established. Therefore, the number of worms in the lungs Could not be deducted exactly from faecal lungworm larvae counts.