Equipment deadspace can be a hazard in drug administration. The aim of this study was to measure the size of this problem. The deadspaces of a selection of cannulae, syringes and epidural catheters were measured by displacing the deadspace volume with water and measuring the weight gain. Between 10 and 30% of a 1-ml intravenous dose will remain in the deadspace depending on the type and gauge of the cannulae. The deadspace of an epidural catheter and filter is approximately 1 ml. All cannulae should be flushed after drug administration. Epidural catheters must be flushed with the same solution as the test dose before insertion.