We report on two young patients with massively elevated CA-125 serum level of 290 and 264 U/ml respectively, who clinically exhibited suddenly occurring ascites. The diagnosis of ovarian carcinoma or ruptured ovarian cystoma led to a laparotomy. During the operation, a disseminating granulomatous inflammation was evident, which was identified histologically and microbiologically as miliary tuberculosis with peritoneal invasion. CA-125 was immunohistochemically localised, sharply demarcated around the tuberculous granuloma. A possible explanation for this finding is the inflammatory mesothelial proliferation. A similarity in antigenic structures of membrane components of M. tuberculosis and CA-125 cannot be excluded. Serum CA-125 levels tested 6 months after the treatment of the tuberculosis showed a value within the normal range (less than 35 U/ml).