The Venereal Disease Research Laboratory (VDRL) test has long been considered the best serological test for the diagnosis of neurosyphilis. The goal of this study was to find out if the Rapid Plasma Reagin (RPR) could be an alternative to the VDRL. Cerebrospinal fluid (CSF) and sera samples from patients in the following stages of syphilis were tested: 8 had symptomatic and 16 asymptomatic neurosyphilis, 4 were in the primary stage, 6 had secondary syphilis, and 92 were in the latent stage. We have also studied 61 samples from individuals with treated syphilis and 126 with other neurological diseases than neurosyphilis. All the CSF samples were studied with both RPR and VDRL tests. RPR and VDRL test results were mostly concordant. The specificity of these tests for current neurosyphilis was 99% for the VDRL and 99.3% for the RPR, whereas the sensitivity was 70.8 and 75%, respectively, for the VDRL and RPR. In view of these results it seems to us that the RPR could be an alternative to the VDRL in the diagnosis of neurosyphilis.