Gas and dust in protogalaxies

The study of high-redshift objects is rapidly developing, allowing to build the star formation history of the Universe. Since most of the flux from starbursts comes out in the FIR region, the submm and mm are privileged domains for the exploration at high z. I review the recent work on galaxies at high redshift in this wavelength region, for the continuum as well as for the line detection (dust and molecular gas). Perspectives are discussed to detect early objects (maybe protogalaxies) with the future large millimeter instruments.