The aim of this work was to study the increase in hair contamination by salmonella in cattle between the farm and slaughterhouse and to explore the possible relationship between this contamination and the contamination of carcasses and of the ground beef made from these animals. Between April 1994 and May 1995, eight groups of ten cows were sampled at different stages during transportation between the farm and the slaughterhouse and on the slaughterline. For each group, one or two cows were included in each group because they had been shown to excrete Salmonella typhimurium 15 days before slaughtering. Samples were collected from the animals (faeces, hide, carcasses, lymph nodes, ears), from the environment (vehicles, cubicles, loading corridor, stunning area) and from the final product (ground beef). The hair samples as well as the environmental samples were the most frequently contaminated (26 to 69%). Eleven different salmonella serotypes were identified, with a maximum of three different serotypes per sample. The typhimurium serotype was isolated from 67% of the positive samples. For the animals leaving the farms, the frequency of hair contamination by serotype typhimurium was 8%. The step that most influenced hair contamination seemed to be the transportation to the slaughterhouse with the contamination frequency reaching 25%. The time spent by the animals in the cubicles of the waiting area of the slaughterhouse seemed to have little influence on the frequency of hair contamination. Even though the frequency of coat contamination reached 25% (for serotype typhimurium) at the beginning of the slaughterline, carcass contamination was only 1% before chilling and only involved one group of animals. In this group, hair contamination after slaughter (serotype typhimurium) reached 90% (9/10), and 80% (4/5) of the samples taken from the ground beef were positive (serotype typhimurium). No contamination was detected in the ground meat made from the other groups.