Measurements of the individual multiplicities of pi (+), pi (-) and pi (0) produced in thc deep-inelastic scattering of 27.5 GeV positrons on hydrogen are presented. The average charged pion multiplicity is the same as for neutral pions, up to z approximate to 0.7, where z is the fraction of the energy transferred in the scattering process carried by the pion. This result (below z approximate to 0.7) is consistent with isospin invariance. The total energy fraction associated with charged and neutral pions is 0.51 +/- 0.01(stat.) +/- 0.08 (syst.) and 0.26 +/- 0.01 (stat.) +/- 0.04(syst.), respectively. For fixed z, the measured multiplicities depend oil both the negative squared four momentum transfer Q(2) and the Bjorken variable x. The observed dependence oil Q(2) agrees qualitatively with the expected behaviour based oil NLO-QCD evolution, while, the dependence on x is consistent with that of previous data after corrections have been made for the expected Q(2)-dependence
