Risk indicators for Pasteurella haemolytica related summer pneumonia in lambs in The Netherlands were investigated using a mail questionnaire survey of 860 flocks. The response rate was 64% (n = 550). Multivariate risk analysis indicated that taking sheep to sheep fairs, the purchase of sheep and/or lambs, the lack of possibility for indoor housing, and an increased flock size were associated with increased risk of occurrence of summer pneumonia in lambs of the home flock.