Laser damage thresholds of 8μm- and 22μm-core diameter solid-core photonic crystal fibres (PCF) and hollow-core photonic band gap (PBG) fibres have been measured. The studies were carried out using a 1.06μm Nd:Yag laser (30nsec pulses at 10Hz), which is optimally coupled into these fibres by careful mode matching, providing a coupling efficiency greater than 90%. It has been shown that the damage threshold of the 8´m core PBG fiber occurs at pulse energies close to 1 mJ, equivalent to a fluence well in excess of 1kJ/cm2 propagating down the fibre. This is a factor of 4 larger than the damage threshold of a solid-core PCF of similar core diameter. In comparison, the damage threshold of the large-core PBG is smaller than that of the equivalent PCF. Theoretical modelling based only on the optical modal properties of the single mode PBG fibre shows that an enhancement of a factor of 25 should be obtainable. Thus there are different damage mechanisms potentially responsible for the fragility of larger core PBG fibres. In an experimental study of bend losses it has been found that it is possible to bend the 8μm PBG fibre up to the breaking point bend radius (<1mm). The critical bend radius for the 22μm core PBG is close to 2 mm, which is 50 times smaller than the critical bend radius of a 20μm core PCF.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.