  The proper time path integral representation is derived explicitly for an
arbitrary $n$-point amplitude in QCD. In the standard perturbation theory the
formalism allows to sum up the leading subseries, e.g. yielding
double-logarithm Sudakov asymptotics for form factors. Correspondence with the
standard perturbation theory is established and connection to the
Bern-Kosower-Strassler method is illustrated.
