Full documentation of every case of central venous catheterization is a prerequisite for reducing the incidence of failures and complications. A laboratory computer program already in use was modified for this purpose: the start of the operation is put in in "real time", abandoned or failed procedures or incomplete data are detected, and can be queried on the day of patient is discharged from hospital. Adverse effects are shown up at an early stage by the quarterly print-out. The program involves less work than a conventional system without computer. The experiences gained with this modified system in the course of one year (including the run-in period) are reviewed.