The effect of oral intake of endotoxin (ET) combined with inhalation of ET-contaminated feed-dust was studied in 6 prepubertal gilts. The animals were given 100 mg of ET each in their ordinary feed ration and meanwhile stayed for 4 h in a continuous flow exposure chamber where the endotoxin concentration was approximately 9 micrograms/m3. Blood samples were collected during the exposure and for 8 h afterwards. Bronchoalveolar lavage (BAL) was performed 24-26 h after the exposure. Six additional animals received ordinary feed and were exposed to feed-dust without added ET. Blood samples were analysed for total white blood cell count (B-WBC) and differential count: polymorphonuclear (PMN) and mononuclear (MN); total red blood cell count (B-RBC); platelets (B-PLT); total serum bile acids (S-BA); glutamate dehydrogenase (S-GLDH); and a blood plasma prostaglandin F2 alpha metabolite (15-ketodihydro-PGF2 alpha; P-PG). The major findings were decreased numbers of MN, PMN and B-RBC 3 to 6 h after the start of the ET exposure and increased numbers of neutrophilic granulocytes in the BAL fluid of the ET-exposed animals. It is concluded that a combined oral and airborne ET challenge induces hematological and cytological changes that may contribute to the development of respiratory disorders.