A randomized prospective study was done to compare bone harvest morbidity in the lateral anterior versus the lateral posterior approach to the ilium. One hundred consecutive patients, requiring at least 60 ml of bone for continuity defects of the mandible, were randomly placed in equal groups in these two categories. Assessment of morbidity vectors included pain, ambulation, seroma, and blood loss. Results, in part, identified the posterior ilium harvest to have decreased morbidity in all variables. The reduced morbidity encountered, and the greater quantity of available bone, are both related to the anatomic differences between the anterior and posterior ilium. Accepted disadvantages were increased operating time and the need to turn the patient.