Ovine pulmonary adenocarcinoma (OPA) is prevalent in many sheep producing countries such as the United Kingdom, but the prevalence of OPA is not known in Denmark, where sheep production is less intensive. Our objective was to estimate the proportion of OPA in Danish sheep at slaughter. All adult sheep (n=235) and lambs (n=1245) slaughtered at the largest Danish sheep abattoir, receiving animals from the entire country, were collected from 29th February to 25th April 2016 in a cross-sectional-like study. A total of 1480 pairs of lungs from lambs and adult sheep were examined visually and by palpation. Based on gross examination, 25 animals were suspected to have OPA and were examined in more detail by histology and immunohistochemistry. None had OPA. This is in contrast to previous incidental findings of OPA at two farms in 2014. Based on the sample size of adult sheep examined, the prevalence should not exceed 1.3% if the samples collected were representative of the Danish sheep population. However, for greater accuracy, larger studies would be required if the prevalence is 1-2% or less. The study also highlights the necessity for histological examination for definitive diagnosis when undertaking studies on the prevalence of OPA and other lung diseases.