A short theoretical review of the problem of charge neutrality in semiconductor lasers is presented. It is shown that the global charge neutrality holds in laser structures at any pump currents both at steady-state and non-stationary conditions. In the context of injection lasers with a low-dimensional active region, the charge neutrality condition reads as equality of the total electron concentration in a bulk waveguide region and a low-dimensional active region to the total hole concentration in those regions. It is shown that, due to the fact that at high injection currents each of the electron and hole concentrations in the waveguide region is significantly higher than each of these concentrations in the active region, the global charge neutrality condition in the laser structure at such currents effectively reduces to the charge neutrality condition in the bulk waveguide region, and the local charge neutrality in the low-dimensional active region does not have to hold. Keywords: injection lasers, semiconductor heterostructures, low-dimensional active region, quantum well lasers, quantum dot lasers, waveguide region, charge neutrality.