A method of direct determination of the deuteron D-state probability f
rom the experiment, based on the d up arrow p --> ppn reaction analyzi
s is suggested. Using the known results on the vector analyzing power
in elastic NN-scattering, the values of the overall nucleon polarizati
on and the deuteron vector polarization have been obtained. The probab
ility of the deuteron D-state is estimated to be omega(D) = 0.078 +/-
0.046.