TeX’s algorithm for hyphenation gives up when it encounters an
\accent command; there are good reasons for this, but it means
that quality typesetting in non-English languages can be difficult.
For TeX macro packages, you can avoiding the effect by using an appropriately encoded font (for example, a Cork-encoded font — see the EC fonts) which contains accented letters as single glyphs. LaTeX users can achieve this end simply by adding the command
\usepackage[T1]{fontenc}
to the preamble of their document. Other encodings (notably
LY1, once promoted by Y&Y inc) may be used
in place of T1. Indeed, most current 8-bit TeX font
encodings will ‘work’ with the relevant sets of hyphenation patterns.
With the advance of XeTeX and LuaTeX to the mainstream, a new regime for generating hyphenation tables is in place. For each language, a table is written in Unicode, and “8-bit” versions are generated for use with various LaTeX font encodings. Original sets of patterns remain on CTAN, for use when an older environment is needed.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=hyphenaccents