We present preliminary results from a sample of 127 proton‐nucleon inelastic interactions found by following 271 meters of track length in nuclear emulsions which were exposed to 200 GeV proton beam at N.A.L. Castagnoli's method of determining the primary energy from angular distribution of the secondary particles is checked. The multiplicity distribution parameters, i.e., 〈nch〉, D and f, are calculated. The prong distribution from 2 to 20 tracks is found to be broader than a Poisson's distribution.