A 25-year-old mare was examined for persistent colic. Over the previous month, the mare had experienced several episodes of mild recurrent colic. The episode of colic persisted for 18 h and the pain became unresponsive to analgesic therapy. Euthanasia was undertaken. Post mortem examination revealed an atypical infiltrative lipoma of the mesojejunum, confirmed histopathologically. To the authors' knowledge, this is the first case report of a diffuse infiltrative lipoma of the equine mesojejunum.