The study was conducted in Gondar town from November to March 2010 with the objectives of determining the prevalence, identifying the species involved and assessing possible risk factors of lung worm infection in small ruminants. The overall prevalence of lung worm infection in the study was 33.83% and 32.6% in coproscopic and postmortem findings respectively. Age, sex, management system, month and species of animal were taken as risk factor for the occurrence of lung worm infection. There were no significant difference (P>0.05) between age, sex, management system, month and species of animal. The prevalence of lung worm infection was 30.43% and 36.22% in coproscopic examination and 31.74% and 34.92% in postmortem findings in sheep and goats respectively. The prevalence of lung worm was 36.22% and 30.43% in coproscopic and 27.27% and 35.91% in postmortem in female and male respectively. Prevalence of 42.85%, 32.93%, 28.57% and 37.75% were observed in animals of age groups less than six months, six month to two years, two years to four years, and greater than four years respectively. Prevalence of 39.47%, 30.08%, 33.33%, 34.88%, and 31.57% were observed in November, December, January, February, and March respectively. The prevalence between management systems was higher in extensive (34.40 %) than semi-intensive (30.90%). Dictyocaulus filaria has the highest prevalence (15.86%) than Muellerius capillaries and Protostrongylus refescens.