The free amino acids of the freshly prepared juice of Viscum album var. mali L. were isolated and determined quantitatively. There was a surprisingly high content of proline and especially arginine, usually found only in protamine hydrolysates. The absence of some of the important plant amino acids, particularly glutamine and asparagine was also noted. These and other peculiarities discussed in the paper seem to be of interest in relation to the unusual over-all metabolism of mistletoe and its cancerostatic properties. The isolation and the identification of the components is described.