Crude extract of Juniperus excelsa (JeExt), which tested positive for the presence of anthraquinone, flavonoids, saponins, sterols, terpenes and tannin, exhibited a protective effect against castor oil-induced diarrhoea in mice at 100-1000 mg/kg. In rabbit jejunum preparations, JeExt (0.01-1.0 mg/mL) caused relaxation of spontaneous and K(+) (80 mM)-induced contractions at similar concentrations to papaverine, whereas verapamil was relatively more potent against K(+). JeExt (0.03-0.3 mg/mL) shifted Ca(2+) concentration-response curves to the right, like papaverine or verapamil. JeExt (0.003-0.01 mg/mL) caused a leftward shift of isoprenaline-induced inhibitory concentration-response curves, similar to papaverine. JeExt (1.0-30 mg/kg) caused suppression of carbachol (CCh, 100 μg/kg)-induced increase in inspiratory pressure of anaesthetized rats. In guinea-pig trachea, JeExt (0.001-3.0 mg/mL) relaxed CCh (1 μM)- and high K(+)-induced contractions and shifted isoprenaline-induced inhibitory curves to the left. This study suggests that Juniperus excelsa possibly exhibits a combination of Ca(2+) antagonist and phosphodiesterase inhibitory effects, which provides a pharmacological basis for its traditional use in disorders of gut and airways hyperactivity, such as diarrhoea, colic and asthma.