Pooled swab sample results were obtained from 22 different Danish slaughterhouses of varying sizes from July 2002 to June 2008. The smallest slaughterhouse slaughtered 242 pigs per day on average, and the largest slaughterhouse slaughtered 11 ,200 pigs per day. A full dataset could be obtained for 17,180 swab pools. Five carcasses were swabbed with a gauze swab after cooling and pooled into one sample which was analysed for salmonella. For each pool, serological results from the herds represented in the pool ·were obtained from the Danish Zoonoses register. One year's data from each herd was used to assign a seroprevalence for each carcass. For each slaughterhouse we calculated the salmonella "burden" of the slaughter day by multiplying the number of pigs transported to the slaughterhouse and the serological prevalence of the particular herd. The results were analysed using a generalised, linear mixed model with serological status of the herds of origin for the sampled pool, salmonella burden of the day as fixed effects, and slaughterhouse as a random effect.