Central venous cannulation (CVC) is a procedure frequently performed by house staff in the intensive care units of teaching hospitals. In the medical ICUs of our two hospitals, CVC was successfully done by house officers in 172 cases requiring 231 attempts (one operator at one insertion site), for a success rate of 74%. There were 14 complications (6.1%), five requiring intervention, but none fatal. The overall success rate was higher for the internal jugular approach and lower for the external jugular approach than for other sites. The success rate for Swan-Ganz catheterization was higher for the internal jugular than for the subclavian approach. CVC during resuscitation was frequently unsuccessful (41%) and/or complicated (13.6%). Although success rates were comparable, complications were more common among experienced house officers than among interns, perhaps reflecting patient selection. There was a trend toward fewer and/or less severe complications during the course of the month and of the study.