The authors describe in their case study the history of a 51 year old man, at whom they verified without thoracotomy thoracal actinomycosis. They achieved recovery giving permanently high doses of Penicillin. In connection with this rare case the authors review pathogenesis, the symptomatology, the diagnosis and the therapy of actinomycosis. The authors have found only one case in the Hungarian literature, which was recognized without thoracotomy and was cured by antibiotic therapy within a short period of time.