We report the case of a girl with peritoneal tuberculosis (Tb) who presented with mimicking features of ovarian cancer including massive ascites, elevation of CA-125 and ovarian masses. These ovarian masses cannot be ruled out malingnacy with image study. Gram stain, acid-fast stain, bacteriological and mycological culture of centrifuged ascites cells were negative. Tumor markers revealed an elevated CA-125 level of 112 U/mL and adenosine deaminase level were significantly high with 118 U/L. Diagnostic laparoscopy was done. The histology of the peritoneum and the ovary showed multiple granulomatous nodules with epithelioid cells and multi-nucleated giant cells. And there were no evidence of malignancy. Furthermore acid-fast bacilli (AFB) was identified in this specimen. Peritoneal Tb was difficult to diagnosis in our patient because it mimicked ovarian cancer. And this is the first case of abdominal Tb mimicking ovarian cancer in children in Korea.