The effects of inorganic phosphate on cell growth, accumulation of ginseng saponin (secondary metabolite) and ginseng polysaccharide (primary metabolite), together with nutrient utilisation, were investigated in suspension cultures of Panax ginseng (PG) and Panax quinquefolium strain Q91625 (PQ). The results indicate that the crucial concentration of phosphate for cell growth of PG and PQ was 1.04 and 0.65 mM, respectively. Bound phosphorus content for PG and PQ cells was determined to be 4 and 7 mg P/g DW, respectively, which suggested a more urgent demand of phosphate during cell cultivation of PQ. For simultaneous production of ginseng saponin and polysaccharide, the optimal concentration of phosphate in PG cell cultures was 0.42 mM, and saponin and polysaccharide accumulation was 643 mg litre(-1) and 2.18 g litre(-1), respectively; 1.25 mM of medium phosphate was the best for biosyntheses of saponin (960 mg litre(-1)) and polysaccharide (1.8 g litre(-1)) by PQ cell cultures.