Automatic broiler catching machines have been developed for several reasons. Manual catching is expensive, often rough and may cause injury to the birds. Apart from animal welfare considerations, the demand for good quality meat means that rejection rates must be kept at a low level. The poor working conditions for manual catching teams are also an important factor. Only a few scientific studies on the effects of catching machines on bird health and welfare have been published. In this study, the carcase rejection rates in relation to manual and mechanical catching were compared at a poultry abattoir following a change of loading and unloading systems. The effect on the level of birds found ‘dead on arrival’ at the slaughterhouse initially varied considerably, regardless of catching method. During the last 3-month period of the study however, mechanically caught flocks showed significantly higher frequencies of dead birds on arrival than manually caught flocks. During the same last period, when running-in problems should be regarded as solved, the prevalence of bruises was also still significantly higher in the mechanically caught flocks, whereas the prevalence of fractures did not differ significantly between the two groups. This suggests that there are still opportunities for further improvements of the machine, although in Sweden it has now been accepted for commercial use in accordance with Swedish animal welfare legislation, under the supervision of the National Board of Agriculture.