How many lambda Bootis stars are binaries?

In the attempt to shed new light on the lambda Boo phe nomenon we analyzed the astrometric, photometric and spectroscopic characteristics of stars out of a list of recently selected lambda Boo candidates. We show that the class is still ill-defined and discuss the possibility tha t some, if not most stars presently classified as lambda Boo, are in fact b inary pairs and that peculiar abundances may not correspond to actual value s if the average values of the atmospheric parameters T-eff, and log g are assumed and the effect of veiling is not taken into account.