BackgroundReconstructive breast surgery is now recognized to be an important part of the treatment for breast cancer. Surgical reconstruction options consist of implants, autologous tissue transfer or a combination of the two. The latissimus dorsi flap is a pedicled musculocutaneous flap and is an established method of autologous breast reconstruction.Lumbar hernias are an unusual type of hernia, the majority occurring after surgery or trauma in this area. The reported incidence of a lumbar hernia subsequent to a latissimus dorsi reconstruction is very low.Case presentationWe present the unusual case of lumbar herniation after an extended autologous latissimus dorsi flap for breast reconstruction following a mastectomy. The lumbar hernia was confirmed on CT scanning and the patient underwent an open mesh repair of the hernia through the previous latissimus dorsi scar.ConclusionLumbar hernias are a rare complication that can occur following latissimus dorsi breast reconstruction. It should be considered in all patients presenting with persistent pain or swelling in the lumbar region.