This paper reports the results of a prospective survey of 266 attempted central venous catheterisations by various routes, evaluating their success rate and incidence of immediate complications and attempts to demonstrate a relationship between patient height in centimetres (H) and ideal catheter length. The overall rate of intrathoracic placement was 230 from 239 catheterisations (96%) after 266 attempts (86%). Of these 230 catheters, 54 terminated in the right atrium (24%). To avoid right atrial placement with its well documented risk of cardiac tamponade, it is recommended that right infraclavicular subclavian catheters are inserted to H/10-2 cm, right internal or external jugular catheters to H/10 cm and left external jugular catheters to H/10 + 4 cm.