Actinomycosis is a chronic, suppurative bacterial infection characterized by multiple abscesses, sinus tracts, fibrosis, and granulation involving the face, neck, thorax, or abdomen. Thoracic actinomycosis probably results from aspiration of oropharyngeal secretions. Its description in the literature is extensive. Reported herein are two cases of thoracic actinomycosis with unusual manifestations exemplifying the organism's lack of regard for fascial planes. The authors present a comprehensive review of actinomycosis in order to encourage early diagnosis. The importance of bedside examination and inspection of available material stained by Gram's method are emphasized. Computed tomography scanning is a useful adjunct for assessing the anatomic extent of this disease.