A random sample of 2980 households in the UK in 2007 showed that 26 per cent and 31 per cent of households owned cats and dogs, respectively. Households with gardens were more likely to own cats and dogs than households without gardens. Households in which someone was qualified to degree level were more likely to own cats and less likely to own dogs than other households. Cats were more likely to be owned by semi-urban/rural households and by female respondents. Dog ownership significantly decreased the likelihood of cat ownership, and respondents aged 65 years or more were less likely to report that their household owned a cat than younger respondents. Households with one or more dogs and children aged 11 to 15 years were more likely to own a cat than other households. The likelihood of dog ownership increased as household size increased. Dogs were more likely to be owned by rural households, and less likely to be owned by households with cats or children aged 10 years or younger. Female respondents and those aged less than 55 years were more likely to report dog ownership than other respondents. The estimated size (and 95 per cent confidence intervals) of the owned cat and dog populations in the UK in 2006 was 10,332,955 (9,395,642 to 11,270,269) cats and 10,522,186 (9,623,618 to 11,420,755) dogs.