Our observations aimed at determining the effects of supplementation with aluminium of plant emissions on specific ovalbumin antibody production in sheep by means of an ELISA method. Eleven Merino ewes aged 2.5 years were included in the experiment. The experimental group consisted of 6 animals. The daily intake of 0.75 g substrate per animal was administered after the morning feeding via a laryngeal tube. The amounts of essential and risk elements included in the substrate are given in Tab. I. All animals were subcutaneously immunized with ovalbumin (OVA, SIGMA A 5503) in 10% alhydrogel (Superhpos Ltd., Denmark) at a dose of 0.2 mg per 10 kg of live weight. The first immunization took place prior to the first gavage of emissions, the second one on day 21 of the experiment. Blood samples from the v. jugularis were collected from all animals, prior to the first immunization, in 6 weekly intervals and then in the 8th and 10th week of the experiment. A modified ELISA method (Strobel, 1983) was used to determine specific OVA antibodies in the sera. Throughout the observation period the increase of OVA antibody production appeared to be more significant in the experimental sheep. In the latter, increased specific antibody production could be detected as early as in the 1st week with maximum immunoglobulinaemia occurring in weeks 3 and 6 after OVA administration. As to specific antibody concentrations, significant differences between the experimental and the control ewes were recorded in weeks 2, 3, 4, 5 and 6 of the experiment (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)