Abundances of massive stars: some recent developments

The last few years, we have witnessed a large increase in the amount of abundance data for early-type stars, which have been very useful in various fields of astrophysics (e.g. mixing processes in stars, chemical evolution of galaxies). Two intriguing results emerging since the last reviews on this topic (Herrero 2003; Herrero & Lennon 2004) will be discussed: (a) nearby OB stars exhibit metal abundances generally lower than the solar/meteoritic estimates; (b) evolutionary models of single objects including rotation are largely unsuccessful in explaining the CNO properties of stars in the Galaxy and in the Magellanic clouds.