Differences in haematological and clinicochemical profiles of blood of apparently healthy slaughter pigs collected at the farm and at slaughter were investigated in relation to the severity of pathological-anatomical lesions. For this purpose blood-samples of castrated male pigs were collected once at seven different farms and from the same pigs one to three days later at the slaughterhouse. In general, as far as the investigated blood variables are concerned, there were distinct and significant differences in the mean values between farm and slaughter blood-samples. As a rule the mean values of the investigated blood variables were higher in the slaughter blood than in the farm blood. The effects are most pronounced for leucocyte concentration and for the activity of the enzymes creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and gamma-glutamyltransferase (gamma-GT). For the blood variables albumin, lymphocytes and magnesium there were significant, but not so strong interactions between the sites of blood-sampling and the groups, which were classified according to the severity of pathological-anatomical lesions. Despite the fact that there were significant differences in the mean values of blood profiles of the slaughter pigs between the sites of blood sampling, this effect was only manifest as a difference in the level of the values of the blood variables. This means that clinicochemical and haematological profiles from groups of pigs at slaughter reflect the herd's health status at the farm and can be used when monitoring it.(ABSTRACT TRUNCATED AT 250 WORDS)