We examined the natural course of athletically active young people with back pain and a diagnosis of spondylolysis (stress fracture of the pars interarticularis of the facet joint of the lumbar spine). We limited the study to those with "subtle" fractures (normal radiographs and positive bone scans) and used computed tomography scanning to further characterize this lesion and to determine whether we could demonstrate healing in this population. The study group included 40 patients with low back pain and a diagnosis of spondylolysis by nuclear medicine study. Computed tomography scans were performed with both traditional cuts and reverse-gantry angled cuts to help determine long-term treatment and prognosis. Forty-five percent of patients (18) demonstrated chronic nonhealing fractures, 40% (16) demonstrated acute fractures in various stages of healing, and 15% (6) demonstrated no obvious fractures. With the diagnosis of spondylolysis being fairly common in young athletes with low back pain, primary care physicians need to have a high index of suspicion in making the diagnosis. Computed tomography scans can play a very important role in diagnosis, assessment of the defect, short-term and long-term management decisions, and in determining prognosis.