Studies on the incidence and spectrum of complications and prognostic factors in adults with pneumococcal meningitis are scarce. Therefore, we analysed 87 consecutive cases who were treated in our department between 1984 and 2002. Meningitis-associated intracranial complications developed in 74.7% and systemic complications in 37.9% of cases. Diffuse brain oedema (28.7%) and hydrocephalus (16.1%) developed more frequently than previously reported. The incidences of arterial (21.8%) and venous (9.2%) cerebrovascular complications were also very high. Furthermore, 9.2% of cases developed spontaneous intracranial haemorrhages (two patients with subarachnoid and two with subarachnoid and intracerebral bleedings, all in association with vasculitis; one subject with intracerebral haemorrhage due to sinus thrombosis; and three cases with intracerebral bleedings of unknown aetiology). Other new findings were the incidence of acute spinal cord dysfunction due to myelitis (2.3%) and that of hearing loss (19.5% of all patients and 25.8% of survivors). The in-hospital mortality was 24.1%. Only 48.3% of the patients had a good outcome at discharge [Glasgow Outcome Scale Score (GOS) = 5]. Outcome did not change during the study period, as mortality and GOS were similar for patients treated between 1984 and 1992 and for those treated between 1993 and 2002. Factors associated with a bad outcome (GOS </= 4) were chronic debilitating diseases, low Glasgow Coma Scale Score and focal neurological deficits on admission, low CSF leucocyte counts, pneumonia, bacteraemia and meningitis-associated intracranial and systemic complications. Low CSF leucocyte counts were also associated with the development of meningitis-associated intracranial complications. Age > or =60 years was associated with a higher mortality (36.7 versus 17.5%), but the GOS of the survivors was comparable to that of the surviving younger patients. The causes of death were mostly systemic complications in the elderly and cerebral complications in the younger patients. A haematogenous pathogenesis seemed likely in asplenic patients, while contiguous spread from sinusitis or otitis was the major cause of meningitis in non-asplenic individuals. Furthermore, asplenic patients had a raised incidence of meningitis-associated intracranial complications, but their outcome was similar to that of non-asplenic subjects. The morbidity and mortality of pneumococcal meningitis in adults are still devastating. We report higher incidences (diffuse brain swelling, hydrocephalus, cerebrovascular complications) or new incidences (myelitis, hearing loss, subarachnoid bleeding) of intracranial complications. Our detailed analysis of prognostic factors may help clinicians to identify patients at risk and may also be helpful in the design of clinical trials.