i will discuss three questions in this talk. (existence) given a smooth hypersurface y of a projective manifold x with numerically trivial normal bundle, does there exist a codimension one foliation on x having y as a compact leaf? (abelian holonomy) what can we say about foliations having a compact leaf with abelian holonomy? (factorization) it is rather easy to construct foliations on projective surfaces having compact leaves with non-solvable holonomy. in higher dimensions, the only known examples are pull-backs of foliations on surfaces through rational morphism. is this a general phenomenon? in particular, does the holonomy of compact leaves factor through curves when non solvable? (joint work with b.claudon, f. loray, f. touzet)