We analyse the dynamics of on-line learning in multilayer neural networks w
here training examples are sampled with repetition and where the number of
examples scales with the number of network weights. The analysis is based o
n monitoring a set of macroscopic variables from which the training and gen
eralisation errors can be calculated. A closed set of dynamical equations i
s derived using the dynamical replica method and is solved numerically. The
theoretical results are consistent with those obtained by computer simulat
ions.