Many recent works claim that primary antiphospholipid syndrome cannot be clinically distinguished from M.S. Conversely, some patients with true M.S who have some atypical clinical features exhibit aCL antibodies. For this purpose, this work is designed to assess the role of anticardiolipin antibodies in MS and to evaluate whether the presence of these antibodies is an indicator of disease activity and/or the prognosis. Mean while we try to find if these antibodies are related to the type of MS and to the presence of atypical clinical presentation of the disease.  Subjects and Methods: Twenty patients with clinically definite M.S were included in this study. They were submitted to thorough neurological examination [including assessment of disability by Expanded Disability Status Scale (EDSS)], routine laboratory work, visual, brain stem and somatosensory evoked potentials, MRI brain and MRI spine when needed. Detection of aCL antibodies both IgM and IgG in sera of the subjects using ELISA technique was done. The patients were compared to 10 normal controls matched for age and sex. Results: statistically significant increase in the maen level of IgM aCL was found in M.S patients compared to controls (P=0.017). The level of IgM and IgG aCL were correlated positively with EDSS and the number of relapses. Also, it was found that higher level of both IgM and IgG aCL was found in M.S patients with progressive course (secondary progressive) and in patients with abnormal MRI and abnormal evoked potentials. No significant relation was found between aCL antibodies and the presence of atypical presentation of M.S, the duration or the activity of the disease. In conclusion, some patients with M.S especially those with marked disability, progressive form, high relapse rate and to some extent those with atypical clinical presentation should be screened for aCL antibodies . This in turn may help in the therapeutic approach and in the prognosis of the disease.

(Egypt J. Neurol. Psychiat. Neurosurg., 2005, 42(1): 35-47).