  We give an analytic characterisation of the interpolating sequences for the
Nevanlinna and Smirnov classes. From this we deduce a necessary and a
sufficient geometric condition, both expressed in terms of a certain
non-tangential maximal function associated to the sequence. Some examples show
that the gap between the necessary and the sufficient condition cannot be
covered. We also discuss the relationship between our results and the previous
work of Naftalevic for the Nevanlinna class, and Yanagihara for the Smirnov
class. Finally, we observe that the arguments used in the previous proofs show
that interpolating sequences for ``big'' Hardy-Orlicz spaces are in general
different from those for the scale included in the classical Hardy spaces.
