  We compare the structure of the tree level scattering amplitudes in
non-Abelian tensor gauge field theory and in open string theory with Chan-Paton
charges. We limit ourselves considering only lower rank tensor fields in both
theories. We identify the symmetric and antisymmetric components of the second
rank tensor gauge field with the string excitations on the third and forth
levels. In the process of this identification we have been selecting only those
parts of the tree level scattering amplitudes in the open string theory which
have dimensionless coupling constants in four dimensions. It seems that this
subclass of tree level scattering amplitudes may provide important information
about the structure of the open string theory and most probably it is
equivalent to the non-Abelian tensor gauge field theory.
