The zero bound issue is only one aspect of the optimal inflation problem. The other aspects relate to the adverse effect of zero inflation on wage negotiations (as proposed by Akerlof et al.), or asset market inflation under observed rates verging towards zero. The problem of zero bound can thus be regarded as an important element of the debate seeking to determine whether zero inflation rate is optimal for the economy. As Japan's recent experience shows, zero bound has ceased to be a theoretical curiosity and has become a subject of lively debates amongst researchers. The paper aims to approximate the main themes of this debate. Following introductory remarks, the author proceeds to discuss alternative interpretations of the zero bound problem. Part three of the paper presents the findings of simulations by different authors of the economy's responses under zero bound conditions. The fourth part deals with conclusions arising from historical evidence. Finally, part five formulates monetary policy recommendations aimed at preventing or eliminating zero bound.