We have established primary cell culture of the marine demosponge Dysidea avara and Suberites domuncula. Microbial contamination was controlled by the use of a pool of antibiotics confirming the goodness of this procedure. Effect of pH, temperature and light was studied to establish the better growth conditions. The comparison of lipid composition of sponge and cells suggested a series of experiments to optimise the medium. A glucose dose-dependent experiment showed that the ideal glucose concentration is 1 g l(-1). Supplementing the medium with unsaturated fatty acid and retinol, no promotion of growth was observed, but the compounds were totally metabolised by cells. Increments from 70 to 160% in the number of cells were observed, supplementing the medium with different concentration of cholesterol. These results suggest that the analysis of the chemical composition of sponge and cells give indication on the composition of the nutrient media.