The most frequent cause of spontaneous subarachnoid hemorrhage (SAH) is rupture of intracranial arterial aneurysms (> 70%). The remainder are due to many different aetiologies. Although SAH is a relatively common neuropathological finding in systemic lupus erythematosus (SLE), it is normally due to the extent of the intercerebral hemorrhage and not to its isolated presentation. We report the case of a 34 year old woman who presented with non-traumatic SAH at the onset of her lupus disorder. The patient was attended for SAH and at the same time a multisystemic disorder and severe thrombocytopenia were found, leading to a diagnosis of SLE. The neuroimaging techniques, selective cerebral arteriography, cerebral and spinal magnetic resonance, and magnetic resonance angiography did not show any vascular malformations. The patient was treated with immunosuppressive therapy, nimodipine, and following angiographic tests, with antiaggregants and anticoagulants. The greater frequency of SAH in patients with lupus, as compared to the general population, has been attributed to the presence of intracranial vasculitis. However, neuropathological studies have shown that true vasculitis is very infrequent in the central nervous system of SLE patients. In the case we describe, the first in which SAH appeared at the onset of the disease, we consider that the origin of the hemorrhage was her high arterial blood pressure and thrombopenia.