We have developed a laser pointing system, the GestureLaser, which allows a remote operator to control a videocamera and a laser beam via a networked personal computer. The laser spot can be moved by the mouse cursor controlled by the remote instructor. The system was tested by giving remote instruction in thoracentesis to inexperienced operators using a training mannekin. Seven medical students received instructions using the laser pointer and another seven received instruction without the laser pointer. All operators completed the task correctly. The laser pointer group correctly identified the centesis space and performed the task on the first trial. When the laser pointer was not used, four operators (57%) made a mistake in selecting the centesis space at the first trial. The mean times for both stage 1--verbal versus GestureLaser 59 s (SD 13) versus 44 s (SD 5), p = 0.015 - and stage 2--verbal versus GestureLaser 98 s (SD 20) versus 64 s (SD 7), P = 0.002 - were significantly shorter when the GestureLaser was used. The study shows that the laser pointing system can be used to remotely instruct a novice operator in performing thoracentesis. It could improve collaboration between geographically separated sites.