Compared with conventional adhesive systems, adhesive precoated (APC) are reported to have advantages in clinical use. The ex vivo bond strength to human premolar teeth of metallic and ceramic APC brackets was compared with that of identical brackets bonded with Transbond (3M Unitek) light cured orthodontic adhesive, and patterns of failure were examined. There was no significant difference (P > 0.05) in mean bond strength between metallic brackets bonded with the two systems. Ceramic brackets bonded with Transbond had significantly higher (P <0.05) mean bond strength and failure more normally occurred at the composite/enamel interface when compared with APC ceramic brackets and metallic brackets. Following debonding no enamel damage was observed with either APC or conventionally bonded ceramic brackets.