The present study demonstrates that various fractions and sub-fractions isolated from Bacopa monniera produced significant inhibition of carbachol-induced bronchoconstriction, hypotension and bradycardia in anaesthetized rats. All these showed more potency towards inhibition of tracheal pressure compared to either blood pressure or heart rate. The sub-sub fraction and compound 1 caused greater inhibition of tracheal pressure and heart rate compared to blood pressure. Thus, overall bioassay-directed fractionation of B. monniera improved the bronchodilatory activity in various fractions and compound 1 (2-219x) in anaesthetized rats. In vitro, the KCl-induced contraction was equally inhibited by crude extract, petroleum ether and methanol fractions on trachea suggesting bronchodilatory activity remained the same in fractions. On pulmonary artery petroleum ether, dichloromethane and methanol fractions produced 2-2.6 times more vasodilatation compared to crude extract of B. monniera. Subsequent sub-fractions failed to show the existence of broncho-vasodilatory activity, however, the CHCl(3)/MeOH sub-fraction significantly reduced the acetylcholine-induced contraction on ileum. Both the methanol fraction and CHCl(3)/MeOH sub-fraction caused marked reduction of barium chloride-, potassium chloride- and calcium chloride-induced contraction on guinea-pig ileum, indicating their interference with Ca(2+) ion movement. Thus, it may be concluded that various fractions derived from B. monniera possess broncho-vasodilatory activity, which is attributed mainly to inhibition of calcium ions.