We conducted the current review of the paraneoplastic neurologic syndromes (PNSs) associated with gynecologic and breast carcinomas to describe their clinical and immunologic characteristics and their relative frequency. We retrospectively reviewed 92 patients whose serum was sent to our laboratories to detect onconeural antibodies and who were diagnosed as having PNSs associated with breast or gynecologic tumors. PNSs were defined as "definitive" and "possible" (atypical PNS, no onconeural antibodies, and no improvement after tumor treatment). Forty-nine patients had breast and 43 had gynecologic cancer. Sixty-three patients had onconeural antibodies (50 Yo-ab, 5 Hu-ab, 5 Ri-ab, and 3 amphiphysin-ab). Cerebellar ataxia represented 57 (62%) of all PNSs and was associated with anti-Yo in 88%. All Yo-abnegative patients had breast cancer; 4 of them had a mild cerebellar syndrome that improved after tumor treatment. Sensorypredominant neuropathies were present in 17 (18%) patients. Seven of them had Hu-ab (5) or amphiphysin-ab (2). Other PNSs were opsoclonus-myoclonus syndrome (4 cases, Ri-ab in 2), sensorimotor neuropathy (4 cases), paraneoplastic encephalomyelitis (4 cases, Ri-ab in 3), paraneoplastic retinopathy (2 cases), amyotrophic lateral sclerosis (2 cases), stiff-person syndrome (1 with amphiphysin-ab), and limbic encephalitis (1 case). All patients with gynecologic cancer presented definitive PNS, and onconeural antibodies were diagnosed in 93% of them. In contrast, 20% of PNSs associated with breast cancer were defined as possible and the incidence of onconeural antibodies was 51%, excluding the 2 patients with paraneoplastic retinopathy in whom antiretinal antibodies were not analyzed. In patients with possible PNS, a coincidental association between the tumor and the neurologic disorder cannot be excluded.