Nuclear magnetic resonance (NMR) and X-ray computed tomographic (CT) imaging of the brain were performed on nine patients with clinical evidence of cerebral involvement by systemic lupus erythematosus (SLE). Focal lesions were demonstrated in eight patients by NMR and in six by CT. The examinations with both techniques were negative in one patient and showed essentially identical pathological conditions in three patients. In three patients NMR demonstrated more numerous lesions than CT. All lesions seen on CT were also seen on NMR, mostly with greater clarity and extent. In view of the limited number of patients, this study is preliminary, but it appears that NMR demonstrates more accurately the degree of brain involvement in SLE than CT.