Abstract: A sperm-blocking agent is disclosed. The composition comprises an aqueous solvent a gum which is a polysaccharide having about 0.3 to 10 wt % of the composition, wherein the polysaccharide is selected from the group consisting of celluloses and their derivatives, hemi-cellulose, fiber, starches and their derivatives, polydextrans and their derivatives, pectins and their derivatives, seaweed polysaccharids, their salts and derivatives and natural gums; and a lubricant being alcohols having about 0.5 to wt % of the composition, wherein the alcohol is at least one selected from polyethene glycol having a molecular weight of over 200, polypropylene glycol having a molecular weight poly(ethylene oxide) polymers and glycerin; wherein the viscosity of the composition is above 9000 cst.