Objective. To correlate the spin-spin relaxation time (T2) of brain tissue in neuropsychiatric systemic lupus erythematosus (NPSLE) with the patient's clinical condition.Methods. T2 values were determined in 54 SLE patients and 45 non-SLE cointrols at 1.5 Tesla, using intensity from multi-echo magnetic resonance (MR) images fitted to an exponential decay curve with rateconstant T2.Results. The T2 of white matter was increased in SLE patients compared with controls (P = 0.01) and was increased in those patients who had previously experienced major NPSLE. Conclusion. Quantitative T2 measurement extends the utility and sensitivity of conventional MR imaging for evaluating NPSLE.Magnetic resonance imaging (MRI) has had an increasing role in the evaluation of neuropsychiatric (NP) symptoms associated with systemic lupus erythematosus (SLE) (1-10). MRI can detect the typical pathology of NPSLE, including focal and diffuse hyperintense lesions, infarcts, hemorrhage, and atrophy, with greater sensitivity than computed tomography (2,9). Although MRI provides excellent anatomic detail, interpretation is limited by the experience and objectivity of the observer, the discriminative ability of the human eye, and the inherent image contrast. MRI can provide quantitative data regarding the relaxation properties of water in different chemical environments induced by inflammatory diseases of the brain (1 1). Spin-lattice relaxation time (TI) and spin-spin relaxation time (T2) provide information regarding the total water in brain, the compartmentalization of brain water, and the degree of association between this water and macromolecules such as myelin and protein (12). The total quantity of water (proton density), T1, and T2 are responsible for the image intensity in both normal and abnormal tissues.Pathologic processes, including edema, infarction, and inflammation, usually increase both T2 and proton density. T2 values have been reported to be elevated in normal-appearing white matter of SLE patients and other patients with inflammatory brain disease (13). The current study determined the T2 values of cerebral lesions and normal-appearing brain