This work was an approach to waste date products valorization through biomass production with the yeast Saccharomyces cerevisiae. The cai bon and nitrogen sources of a semi-synthetic fermentation medium were substituted by date-coat (fleshy part) sugar extract, date-seed hydrolysate, and ammonium nitrate. This modified medium was enriched with date-seed ash and date-seed lipid. Date-coat sugar extract as a carbon source was found to be satisfactory at a concentration of 25 g/l (expressed as its glucose concentration) and date-seed hydrolysate as a nitrogen source was equally suitable at 25 g/l. The addition to the medium of 1.0 g/l ammonium nitrate increased the efficiency of yeast biomass formation, as did phosphorus, which produced a maximum when the medium was supplemented with about 6.0 g/l KH2PO4. The presence of 1 g/l date-seed lipid in the medium also increased the efficiency of biomass formation. Finally, the addition of date-seed ash (0.6 g/l), as a mineral source, to the fermentation medium could substitute for MgSO4 and CaCl2 of the semi-synthetic medium. (C) 1997 Elsevier Science Ltd.