Paraneoplastic cerebellar ataxia is a paraneoplastic neurological syndrome (PNS) that can be the first clinical manifestation of underlying cancer. It is usually associated with onco-neuronal antibodies and has no other specific paraclinical feature. After the surgical and oncologic treatment of the primary cancer, the remaining neurological symptoms have limited therapeutic options. We describe a case of severe ataxia as the primary manifestation of ovarian cancer, with a significant clinical and paraclinical improvement of the neurological symptoms after 20 sessions of rTMS intervention.