The differentiation between a chronic cryptococcal meningitis and a chronic tuberculous meningitis may cause problems for the clinician only if standard microbiological methods are not applied to the diagnosis of both infections. In a male non-AIDS patient (50 y), 11 years after a suggested diagnosis of "tuberculous meningitis", meningoencephalitis with hydrocephalus was diagnosed and treated accordingly without success. Mycobacterium tuberculosis was never found. Because fibrin fibres of a spider web coagulum in the CSF resembled Aspergillus mycelium, the patient was then treated with amphotericin B + flucytosine. Finally, a mycological examination led to the true diagnosis: (1) In the CSF, resembling Aspergillus hyphae were found to be spider web coagulum fibres. (2) Cryptococcal meningoencephalitis based on the detection of Cryptococcus neoformans in CSF and its antigen in serum and CSF. - At post-mortem, cryptococcal meningoencephalitis was established as cause of death. Residual signs of tuberculosis could not be detected in the brain and the meninges. Common clinical similarities of cryptococcal and tuberculous meningitis and the possibility of a double infection are discussed. A comparison of the presence of Cr. neoformans in the meninges of non-AIDS and AIDS patients is made. The formation of spider web coagulum in the CSF is discussed. Proposals for the diagnosis, therapy and prophylaxis of cryptococcal meningitis are made.