All cases of cryptococcal meningitis at Yale-New Haven (Conn) Hospital seen during a 4 1/2-year period were reviewed to calculate the rate of false-negative antigen test results and cultures preceding diagnosis. Of 13 patients, 9 were immunosuppressed and were diagnosed following the initial lumbar puncture, with both antigen test results and cultures positive in all cases. Among 4 nonimmunosuppressed patients, the rate of false-negative antigen test results was 77%, and of cultures, 89%. The diagnosis was consequently delayed in 3, 2 of whom died despite treatment. Cryptococcal meningitis may be underdiagnosed and undertreated to a significant degree in nonimmunosuppressed patients.