The actinomycosis is a chronic suppurative granulomatosis disease. It is owed to a bacillus gram positive; actinomycès israelli. The cervical and thoracic localizations are most frequent. The digestive localization represents 20% of cases. It interest very rarely the pelvis and the genital tracts. We bring back the observation of a patient old of 30 years admitted for mass abdominal. To the exam, the patient had a sensibility of the left hypochondriac area and we found a mass of 6 cm of diameter. To the rectal touch, we found a mass in the bag of Douglas. The echography and the computed tomography revealed a collection under the spleen and a pelvic collection. A rectotomy is performed. The bacteriological study isolates actinomycès israelli. The collection under the spleen is drained under radiological control. Actinomycès israelli is also recovered in the pus brought back by the puncture. The patient is treated by Penicillin. The patient had a favourable evolution. No etiology is found at this patient. For this observation, the collection was accessible to a drainage permitting the diagnosis and the treatment of the actinomycosis while avoiding a mutilated surgery.