Mycobacterium bovis causes gastrointestinal tuberculosis by being transmitted through consumption of infected milk and dairy products, mostly in developing countries, and can spread to the other neighbourhood intra-abdominal tissues and organs. In addition to the symptoms such as weight loss, weakness, abdominal pain, and chronic diarrhea in female patients with abdominal tuberculosis, findings such as pelvic mass, ascites and CA-125 elevation may be encountered. Patients with these symptoms usually preliminary diagnosed as having ovarian cancer. It is very important to distinguish between these two diseases quickly, which have different treatment protocols. In this case report, a case of intra-abdominal tuberculosis caused by M.bovis, whose diagnosis was confirmed by microbiological methods with the findings mimicking ovarian cancer such as weight loss, ascites, pelvic mass and increased CA-125 was presented. Tuberculosis was considered in the differential diagnosis of a 23-yearold female patient with abdominal pain, weight loss, ascites, pelvic mass, and elevated CA-125 (643.9 U/ml) findings and a mass in the left tubaovarian region on abdominal CT. The ileum biopsy sample taken during colonoscopy and ascitic fluid sample taken with paracentesis were sent to our laboratory for acid-fast bacilli (AFB) staining and tuberculosis culture. In our laboratory, samples were incubated in both liquid culture system [BACTEC MGIT 320 Mycobacteria Culture System (Becton Dickinson,USA)] and solid culture medium [Lowenstein-Jensen Medium (Becton Dickinson,USA)] and AFB smears were performed. While AFB smears were negative, ileum biopsy material showed growth on day 14 and ascitic fluid sample on day 11 in liquid culture medium. AFB smear was prepared from broth and red bacilli were seen on a blue background that formed cord factor. The bacillus was identified as Mycobacterium tuberculosis complex by the immunochromatographic rapid test [BD MGIT TBc Identification Test (BD,USA)]. The anti-tuberculosis drug treatment was initiated with the diagnosis of intra-abdominal tuberculosis. The isolated bacillus was found to be sensitive to isoniazid, rifampicin, ethambutol and resistant to streptomycin, according the drug susceptibility test results. Subspecies identification of M.tuberculosis complex was investigated by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) but could not be determined by this method. Genotyping was performed with the GenoType MTBC VER 1.X (Hain Lifescience, HardwiesenstraBe, Germany) kit. The isolate was identified as M.bovis. In the follow-up of the patient three months later, it was determined that tumor markers, ascitic fluid and intra-abdominal lymph nodes regressed significantly and the mass in the left ovary completely disappeared. In this report, we presented a case with intra-abdominal tuberculosis whose clinical, radiological and laboratory findings mimic ovarian cancer to imply the importance of microbiological diagnosis.