Increasing interest in evidence-based medicine has created a demand for accurate and accessible information on activity and trends in clinical practice. A database of all neurosurgery admissions at a teaching hospital maintained by a scientist has been utilised to examine changes in practice and complications from 1977 to 2001. A relational database, set up in 1982, now contains an unbroken record of all neurosurgical admissions at Royal North Shore Hospital (RNSH) since 1976. It supplies information for morbidity and mortality meetings, research and administrative purposes. A total of 23,766 admissions from 1977 to 2001 were examined. Statistical analysis of trends in age, gender, length of stay (LOS), diagnostic mix, surgery rates and complications in admissions was based on diagnostic groupings. Proportions of vascular admissions rose and of trauma admissions fell. Mean age increased significantly for tumour, trauma and spinal patients; geometric mean LOS declined significantly for tumour, spine, vascular, cranial nerve and peripheral nerve groups. Concurrently, inpatient death rate fell significantly for tumour and vascular patients. Deep vein thrombosis (DVT) rose significantly for trauma, vascular, tumour, spinal and infection patients; pulmonary embolism (PE) rose significantly for tumour, trauma and spinal patients. There was no significant change in wound infection rate at approximately 3.5% of all operated patients. Wound haematoma rates fell significantly from 4.0% to 2.9% while the rate of postoperative cerebrospinal fluid (CSF) leak rose significantly from 0.5% to 2.0% of all operated patients. The value of the database is demonstrated by its ability to provide analysis which shows statistically significant changes over time. Declining death rate and LOS indicate improved efficiency in managing patients, but these are offset by rising rates of CSF leak, DVT and PE. Such rises reflect the changing patterns of casemix and surgery performed, and increasing financial pressures on hospital departments.