Proceedings of the British Ornithologists' Union meeting held at Madingley Hall, Cambridge, between the 8th and 10th September, 1993. Papers include: Avian influenza in free living and cage birds; The epizootiology of duck enteritis in Great britain; Molecular biological evidence indicates that migratory birds might be responsible for the world wide distribution of louping ill virus; Ticks and viruses od sea birds; Blood parasites in the life of the Sparrow Hawk; Impact of trichostrongyle nematodes on the population dynamics of Red Grouse; Red Grouse population fluctuations - Role of caecal threadworm (Trichostrongylus Tenius); Impact of chewing lice on energetics, reproduction and survival of Feral Rock Doves; Determinants of helminth parasite richness among birds; Bacterial and parasitic diseases of wild birds - cases submitted to veterinary investigation centres; Bone diseases in captive and free-living wild birds; Avian tuberculosis in captive and free-living waterfowl; Bacterial infections of wild birds; Botulism; and Disease risks to endangered species breeding programmes.