Neoplastic growth is defined as an autonomous and progressive proliferation of cells which, in most cases, is correlated with the presence of a mass or tumor. Neoplasms are rarely reported in wild cats and the indicated treatment is almost always the excision of the new formation. There is a significant increase in the incidence of neoplasms in wild animals under human care, probably related to the increase in the longevity rate of animals kept in zoos. A specimen of ocelot (Leopardus pardalis) showed an increase in the volume of the right testicle and the patient was submitted to imaging and laboratory tests. The diagnosis was conclusive for seminoma and the patient underwent a unilateral orchiectomy. The patient has recovered well and will be followed-up over the next few years to monitor the presence of neoplasm in the body. This is the first report of seminoma in an ocelot.