This talk addresses experiences with non-inferiority (NI) studies in veterinary medicine. In some situations, superiority over placebo cannot easily be demonstrated, e.g. if a placebo is not appropriate for animal welfare reasons. Non-inferiority over an active control may be an alternative. In Europe, NI trials are used relatively often and our experiences will be helpful in stimulating discussion on this topic. In particular, we will address topics such as the pros and cons of a positive control group, animal welfare considerations and speed of recruitment, how to choose an appropriate active control treatment, how to define the non-inferiority margin, do we still need a placebo group, power considerations, non-continuous endpoints (binary, survival), and non-parametric tests. Several examples, mainly from the parasite and pain area, will be used to illustrate the important points.