Ducklings are among the most sensitive avian species to the toxic effects of aflatoxin В1 (AFB1). In this experiment, the toxic effects of AFB1 on liver morphology, blood plasma aspartate amino-transferase (AST), alanine amino-transferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), γ-glutamyltransferase (γ-GT), albumin, blood glucose, and plasma total protein (TP) were established in mulard ducks. The experiment was carried out with four groups of 20 10-day-old ducklings each. Each group included three subgroups with 10 birds. The groups were as followed: group І – control (which received standard feed according to the species and age), group ІІ – experimental, which received compound feed with 0.5 mg/kg AFB1, group ІІI– receiving compound feed supplemented with 0.8 mg/kg AFB1 and group IV – compound feed supplemented with 0.5 mg/kg AFB1 and 2g/kg Mycotox NG. The experiment lasted for 42 days. Macroscopically, livers were enlarged, rounded, with yellowish colour and a frail consistency in group ІІ and ІІI. Histopathologically, a various extent of dystrophy was detected depending on the dose of ingested toxin. The supplementation of compound feed with the mycosorbent Mycotox NG improved deviations in blood biochemical parameters and substantially reduced the severity and prevalence of histological lesions.