The metabolism of galanthamine hydrobromide (Nivalin®) was investigated in rat and rabbit liver homogenates. Experiments were carried out varying several parameters of incubation: substrate (galanthamine hydrobromide, galanthamine, galanthaminone and epigalanthamine), cofactor enrichment (NADPH, NADP/G-6-P, NAD), pH (7.4 and 9.3), time of incubation. Substrates and metabolites were identified and quantitatively determined by GC/MS. In vitro metabolism in rat liver homogenate was negligible. The experiments with rabbit liver homogenate indicated, that galanthamine was actively metabolised the major metabolites being the oxidised product — galanthaminone, and the isomer of galanthamine — epigalantamine. The experimental results show that the metabolism of galanthamine is substrate and product stereoselective.