Indirect immunofluorescence was applied to achieve the rapid diagnosis of enteroviral meningitis within hours of receipt of the specimen. Cerebrospinal fluid (CSF) leukocytes from 40 patients were studied by a method adapted to utilize combination antiserum pools in conjunction with indirect immunofluorescence, and results were compared to those of conventional isolation and serological techniques. When virus was isolated from the CSF (17 patients), there was general agreement with the virus identified by immunofluorescence staining of CSF leukocytes. The advantages of immunofluorescence were particularly striking in 19 patients from whom virus could not be isolated from the CSF and in 4 patients from whom virus could not even be isolated from the throat or rectum. By immunofluorescence, virus was detected in 20 of 21 of these patients. Overall, the rapid immunofluorescence findings were confirmed by the slower conventional methods in 32 of 33 cases. Economy of both time and materials was made practicable by use of the LBM combination antiserum pools, which allow 42 antigenic types to be identified in a single set of 8 simultaneous tests.