Abstract: Neuropsychiatric manifestations of SLE are frequent and usually serious, convulsion is one of the most important and hazardous symptoms of CNS-LUPUS. Because there are many differences in clinical manifestations frequency and severity of organ systems involvement, and cause of death in patients with SLE (in Iran and other countries) an analytic retrospective case-control study was carried out to evaluate the frequency of convulsion in relation with age and sex distribution, the effect of convulsion on patients mortality and prognosis and it's relation with increased levels of Anti-DNA antibodies. With reference to 1001 recoded cases with SLE in Lupus Unit. Rheumatology Research center, Dr, Shariat Hospital Tehran University of Medical science a 393 cases woe included and divide in two groups, convulsive and non convulsive, The frequency of convulsion was 13.3% Male/Female ratio was 1/8.3, with no significant difference between two groups of patients (P>0.05), The most common ago for onset of disease was the second decade a( life (10-19 yrs) in convulsive patients, third decade of life (20-29 yrs) in non convulsive patients, and there was significant differences in second and third decades between tow groups (P<0.05 and odds ratio =1.8). The mean age of onset of disease in convulsive patients was (21.42 + /8.8) which is significantly lower than (24.12+/9.42) those in non convulsive patients (P<0.05). There was no significant difference In frequency of patients in different levees of Anti-DNA antibodies (By RIA technique) in convulsive and non convulsive patients (P>0.05). Mortality rate in convulsive patients was (1.1%) and (7.3%) in non-convulsive respectively, The presence convulsion is associated with an increased mortality date (P = 0.0004 sod odds ratio = 2.6). The most common causes of death in convulsive patients were CNS involvement and infections, pulmonary involvement and infections in non convulsive respectively. CNS involvement was found in more than half (56.5 %). of the expired convulsive patients with no report or death due to CNS . DuK < u in non convulsives. Based on this study as one of the most comprehensive studies wold wide:*There is no significant and positive correlation between occurrence of convulsion and increased levels of Anti-DNA antibodies which are one of the most important serological indices of activity of the disease. *The occurrence of convulsion is an important diagnostic criterion for CNS Lupus that exhibit the severity of SLE. *The Onset of disease in convulsive patients with SLE is earlier than that in non convulsive. The most common cause, of death in Iranian SLE patient sere infections. pulmonary and CN involvements in contrast to the renal failure as the most common cause of death among European and western SLE population, which plays.a less important role in this regard. Our findings confirm the results of the similar studies else where in the world.