The clinical course of Bovine Leukocyte Adhesion Deficiency (BLAD) in eight Holstein Friesian cattle is described. Affected animals were presented with a history of poor thriving and recurrent bacterial infections. Five of these animals had to be killed because of severe respiratory disease shortly after admittance. Three affected animals survived calfhood only as a result of frequent antibacterial treatments. At one year of age, failure to thrive and stunted growth were still evident, but infections requiring antibiotic treatments occurred only sporadically. Clinical manifestations of BLAD were found in the digestive system (gingivitis, periodontitis, alveolar periostitis, diarrhoea), the respiratory system and the skin (impaired wound healing, chronic dermatitis). A leukocytosis based on a mature neutrophilia, which persisted during infection-free periods, was observed in all animals. Granulocytes were substantially deficient of beta 2-integrin expression on their membranes. Anaemia, which was noted in four animals, may be related to the Anaemia of Inflammatory Disease Complex (AID). The serum total protein content increased with time and was associated with elevated gamma-globulin levels. We suggest that, at a certain age, animals affected with BLAD are able to cope with environmental agents due to compensatory mechanisms of the immune system.