The alcoholic extract of the roots of Polygonum hydropiper Linn. was fractionated by column adsorption chromatography. The various fractions obtained were tested for antifertility activity in female albino rats. Petroleum ether, petroleum ether +benzene (1:1 v/v) and benzene +chloroform (1:1 v/v) fractions prevented pregnancy in 8/10, 6/10 and 6/10 albino rats, respectively, while the first two fractions also caused resorption of implants by the completion of term. The other chromatographic fractions did not exhibit any antifertility activity.