  We developed the parameterized post-Keplerian formalism for hybrid
metric-Palatini $f(R)$-gravity. We obtained analytical expressions in the
generel eccentric case for four PPK parameters: $\dot\omega$, $\dot P_{\rm b}$,
$r$ and $s$. Using observational data of PSR J0737-3039 and PSR J1903+0327 we
imposed restrictions on the parameters of hybrid f(R)-gravity and showed that
this theory is not ruled out by the observations in strong field regime. In
addition we obtained predictions for masses of systems components and found
that considered astrophysical objects will be heavier than in GR.
