During 2005, 31 uk veterinary practices participated in a survey of flea infestation, during which 2653 dogs and 1508 cats were examined for evidence of flea infestation and skin disease compatible with flea allergy dermatitis (fad). The prevalence of flea infestation in the cats was 21·09 per cent, significantly (P<0·001) higher than in the dogs (6·82 per cent). The prevalence of skin lesions compatible with fad in the cats (8·02 per cent) was also significantly (P<0·001) higher than in the dogs (3·32 per cent). Flea infestations were more common in households with cats and with more than one pet. Of 467 fleas identified from the cats, 462 (98·93 per cent) were Ctenocephalides felis, one was Ctenocephalides canis, one was Archaeopsylla erinacei, two were Pulex irritans, and one was Spilopsyllus cuniculi. Of 336 fleas identified from the dogs, 313 (93·15 per cent) were C felis, five were C Canis, 12 were A erinacei, five were P irritans, and one was Ceratophyllus (Nosophyllus) fasciatus. Almost half of the owners of the dogs and cats were unaware of their pet's flea infestation. The overall prevalence of fleas and/or skin lesions that could potentially be compatible with fad was 7·46 per cent in the dogs and 22·28 per cent in the cats.