The majority of open myelomeningocele defects are small enough that following the neural repair, soft tissue closure is achieved by simple undermining of the skin edges and tension-free approximation in the midline. The larger defects, greater than 5 cm diameter, cannot be closed reliably by simple skin undermining. Such larger defects call for a close cooperation between the neurosurgeon and the plastic surgeon. In the authors' experience, a reliable, safe method of reconstruction of thoracolumbar and lumbosacral meningomyelocele defects involves the en bloc medial advancement of latissimus dorsi and gluteus maximus musculocutaneous units and reapproximation in the midline. This is the authors' preferred method for all medium and large size defects greater than 5 cm in diameter. This method permits primary closure of the defect in three layers. The flaps are based on the thoracodorsal and superior gluteal vessels and the intervening thoracolumbar fascia. This method provides a tension-free, durable, and viable soft tissue coverage over the dural repair. The flaps do not alter the nerve supply of the muscles involved and merely redefine the muscle origins, without compromising muscle function.