Two commercial laser dendrometers were tested under controlled and fie
ld conditions, and contrasted with alternative instruments. Testing fo
cused on height measurement, but also considered distance and remote d
iameter measurements. Both laser instruments gave very precise estimat
es, but showed some bias. Users of these and other 'high-tech' instrum
ents are reminded that precision is not synonymous with accuracy. User
s should not become complacent about the submillimetre readout, but sh
ould calibrate instruments to examine if users' accuracy requirements
are satisfied. Instruments may need to be re-calibrated each measureme
nt season and after any mishandling.