The luminosity function (LF) is a powerful tool to study the galaxy content and evolution with cosmic time. In the NIR it is less sensitive to dust absorption than corresponding UV-optical estimates. It is thus a better tracer of the overall mass assembly of galaxies and of its rate of growth, revealing itself as a good test-bench for halo models. I will present our recent results on the luminosity function and luminosity density in the NIR, from a composite sample of the deep multi-wavelength surveys MUSYC, FIRES and FIREWORKS. The availability of lower redshift data from the literature also allows us to trace an evolutionary path since z=3.5