Thirty-five merlins (Falco columbarius) were examined post mortem and 13 clinically. Eleven of the latter were captive birds. In eight of the cases examined post mortem no diagnosis could be made but another eight died of a fatty liver-kidney syndrome. Other causes of death included enteritis/proventriculitis (three birds), coccidiosis (three) and septicaemia (two). A variety of incidental findings was noted, for example, parasites and non-fatal lesions. Of the 13 clinical cases, five had bumblefoot and two each had fractures and reproductive failure. There were individual instances of other diseases. The merlin is declining in numbers in Britain and little is known of its susceptibility to disease or causes of mortality. Data on captive birds can provide valuable information in this respect.