A laparotomy was performed in an eleven years-old female Doberman with loss of appetite, abdominal distension and signs of pain revealed multiple structures of a size reaching 1.5 cm, composed of small (6 mm or less), white, cystoid structures, with a total volume of approximately 2 liters. To follow the development of the parasitic organisms, under microscopic observation, their body fragments were also moving without changing place which came out of the abdominal cavity, these masses were transferred to tissue culture flasks containing RPMI containing 20% fetal calf serum and placed in a humidified incubator with 5% CO2 at 37oC. The dog survived only one week after the surgery and the autopsy showed macroscopic parasitic material, either free-floating in the peritoneal cavity or adhering to the peritoneum and viscera. A perforation one cm in diameter was observed in pyloric area on the major curvature, covered by the omentum. No parasites were present in the intestines. Microscopically there were multiple pyrogranulomatous peritonitis, hepatitis and splenitis. The morphologic features of the parasitic material collected at laparotomy were compatible with that of Mesocestoides spp. larvæ. A PCR amplification was performed with mitochondrial 12S rDNA cestod-specific primers. The sequence of the isolates was 89-100% compatible with the reference Mesocestoides corti isolates published in the National Center for Biotechnology Information (NCBI) GenBank.