Studies on the action of L- and D-isomers of amino acids upon motor activity in the clawed toad revealed that most effective among them are basic amino acids (all of them being essential) and hydrophobic amino acids (mainly essential ones). Positive correlation was found between the effectiveness of hydrophobic amino acids on the motor activity of animals and their effectiveness with respect to taste receptors. The data obtained indicate the role of the olfactory receptors in realization of the behavioural reactions of the clawed toads to amino acids.