  We present the first search for binary companions of Massive Young Stellar
Objects (MYSOs) using AO-assisted $K$ band observations, with NaCo at the VLT.
We have surveyed 32 MYSOs from the RMS catalogue, probing the widest
companions, with a physical separation range of 400 - 46,000 au, within the
predictions of models and observations for multiplicity of MYSOs. Statistical
methods are employed to discern whether these companions are physical rather
than visual binaries. We find 18 physical companions around 10 target objects,
amounting to a multiplicity fraction of 31$\pm$8\% and a companion fraction of
53$\pm$9\%. For similar separation and mass ratio ranges, MYSOs seem to have
more companions than T Tauri or O stars, respectively. This suggests that
multiplicity increases with mass and decreases with evolutionary stage. We
compute very rough estimates for the mass ratios from the $K$ band magnitudes,
and these appear to be generally larger than 0.5. This is inconsistent with
randomly sampling the IMF, as predicted by the binary capture formation theory.
Finally, we find that MYSOs with binaries do not show any different
characteristics to the average MYSO in terms of luminosity, distance, outflow
or disc presence.
