  Nuclear parton distributions $f_A(x,Q^2)$ are studied within a framework of
the DGLAP evolution. Measurements of $F_2^A/F_2^D$ in deep inelastic $lA$
collisions, and Drell--Yan dilepton cross sections measured in $pA$ collisions
are used as constraints. Also conservation of momentum and baryon number is
required. It is shown that the calculated $Q^2$ evolution of $F_2^{\rm
Sn}/F_2^{\rm C}$ agrees very well with the recent NMC data, and that the ratios
$R_f^A=f_A/f$ are only moderately sensitive to the choice of a specific modern
set of free parton distributions. For general use, we offer a numerical
parametrization of $R_f^A(x,Q^2)$ for all parton flavours $f$ in $A>2$, and at
$10^{-6}\le x \le 1$ and $2.25 {\rm GeV}^2\le Q^2\le 10^4 {\rm GeV}^2$.
