Actinomycosis is caused by microorganisms of the Actinomyces species, found in the oral cavity, gastrointestinal and genital tract. Infection by Actimomyces species mainly causes chronic supurative disease of the oral cervico-facial, thoracic, and abdominal regions. Clinical manifestations have been described at every level, but the disease is relatively rarely diagnosed. The causative agent is considered to be an opportunistic pathogen associated with infection, trauma, surgical procedures, or associated with a neoplasm or foreign body. Symptoms include intermittent fever, weight loss abdominal or thoracic pain, pseudotumor and tumor masses, and local symptoms from the infected area. Pseudotumor and tumor masses are diagnosed by ultrasonography and computerized tomography. The diagnosis is confirmed by the presence of a causative agent in biopsy or surgically acquired samples. The treatment includes the administration of high doses of antibiotics (penicillin, amoxicillin, ceftriaxone) for at least 6-12 months, as well as surgical tretment. Penicillin is a drug of choice. This infection is often polymicrobial, so that antibiotic therapy should include agents that act against the associated pathogens. Treatment outcome and prognosis in these three cases were excellent, despite the prolonged course of the extensive disease.