  The process of electron--positron annihilation into proton--antiproton pair
is considered within the vicinity of $\psi(3770)$ resonance. The interference
between the pure electromagnetic intermediate state and the $\psi(3770)$ state
is evaluated. It is shown that this interference is destructive and the
relative phase between these two contributions is large ($\phi_0 \approx
250^o$).
