A 12-year-old, spayed Yorkshire Terrier dog with a history of progressive abdominal distension was diagnosed with an ovarian sex-cord stromal tumor. Microscopically, the residual ovarian tissue sample was composed of 2 different tumor cell populations: a luteal-like cell and Sertoli cell components. These cells were notably immunopositive for vimentin, inhibin-α and neuron-specific enolase (NSE). On the basis of all findings, the tumor was diagnosed as luteoma and Sertoli cell tumor of the ovary developing from the ovarian remnant tissue.