Results on charged multiplicity distributions in high energy proton-neutron interactions derived frompd data at 400 GeV are presented. These are compared with other available data onpn distributions at and above 100 GeV. The study reveals that the proton-neutron distribution at 400 GeV do not obey KNO scaling. It has been shown that the negative binomial distribution gives a fair description of the multiplicity distribution and that the early onset of KNO scaling below 400 GeV is approximate.
