A 14-year-old boy presenting with a chest wall mass, pulmonary infiltrate, and scoliosis was found to have thoracic actinomycosis with distal vertebral involvement. Review of the medical literature for the past 25 years revealed only 23 other pediatric cases of thoracic actinomycosis. Clinical, standard radiological, and microbiological findings can be nonspecific. The diagnosis is dependent on a high index of suspicion. A long course of penicillin is the treatment of choice. Body computed tomography is a useful diagnostic aid and is helpful also in evaluating response to therapy.