The antispasmodic activity of extracts from the aerial parts of Buddleja scordioides and Buddleja perfoliata (family: Scrophulariaceae) was studied on isolated tissue preparations from rabbit and guinea pig intestine. The chloroformic extract from the plants exhibited a significant relaxation on the spontaneous contraction of isolated rabbit jejunum at concentrations ranging from 1 to 400 μg/ml, and also caused an inhibitory effect on both K⁺ and Ca²⁺ induced contractions in the same tissue. The extracts at moderate doses (50 μg/ml) reduced 5-hydroxytryptamine (5-HT), acetylcholine and histamine induced contractions on isolated guinea pig ileum. Therefore, B. scordioides and B. perfoliata possess similar relaxant mechanism of action, in view of the fact that both inhibit K⁺ induce contraction and act through serotoninic, muscarinic and histaminic receptors. So, these data support the idea that the extracts may interfere either with calcium mobilization from intracellular stores, or with calcium interaction with regulatory proteins (e.g., calmodulin), or in other steps in the calcium signaling pathway. This leads us to suggest that the spasmolytic effect of both Buddleja species on smooth muscular contractility are due to the same or similar compounds occurring in these two species, which might be present in similar quantities.