  It is surprising to find dust around B type stars, as in the case of B[e]
stars. These stars exhibit a dense, dusty environment witnessed by their
infrared-excess and many emission lines from permitted and forbidden
transitions. Given the large uncertainties on their distances, this spectral
type gathers many different kind of sources that may harbor a similar
circumstellar environment, i.e. a dense dusty disk. At the exception of Young
Stellar Objects, in many cases, it is very difficult to understand the origin
of such a disk without invoking binarity. We describe current powerful methods,
like spectral disentangling, spectro-astrometry and long baseline
interferometry, to detect especially close binaries amongst the unclassified
B[e] stars. The role of binary mergers in the formation of the B[e] phenomenon,
especially in supergiants and compact PNe, is also discussed.
